op chem 1 Flashcards

Question

24.Which of the following has maximum Mass? (A) Electron (B) Proton (C) Neutron (D) Nucleus of Hydrogen

Answer 1

(C) [SSC CGL 2013] Exp: Amu = Atomic Mass Unit Atomic mass unit is defined as the Quantity of element is equal to 1/12 of the mass of an atom of carbon (C12). Mass of the following is given as. Electron = 0.000549 (amu) Proton = 1.00728 (amu) Neutron = 1.00867 (amu) Nucleus of Hydrogen = 1.00783 (amu) So neutron has maximum mass.

Answer 2

(A) Exp: Mass of proton & mass of neutron is same. Mass of the following is given as. Electron = 0.000549 (amu) Proton = 1.00728 (amu) Neutron = 1.00867 (amu)

Answer 3

(B) [SSC CGL Exam. 2013] Exp: The neutrino is so named because it is electrically neutral. It has very small mass & charge. It has spin only.

Answer 4

(A) [SSC LDC 2005] Exp: Neutron is discovered by J. Chadwick in 1932 by Beryllium with -particle that he is awarded by Nobel prize. Neutron is a Neutral particle. 9 4Be + 4 2He 12 6C + 1 0 n Beryllium -particle Carbon Neutron

Answer 5

(A) Exp: M2+ = 2, 8, 14 As metal is dipositive Z = 2 + 8 + 14 + 2 = 26 n = A - Z = 56 - 26 = 30 where n = no. of neutrons Z = Atomic No. A = Mass No.

Answer 6

(A) Exp: Since 6C14, 7N15 and 9F17 have the same number of neutrons equal to 8 (14 - 6 = 8, 15 - 7 = 8, 17 - 9 = 8), these nuclei are isotonic with each other.

Answer 7

(D) Exp: Cyclotron is a type of particle accelerator invented by Ernest Lawrance. It is used to accelerate charged particles to high energies.

Answer 8

(A) [SSC CGL Exam. 2016] Exp: Antiparticle of an electron is positron because it has same mass and charge (but opposite sign) like an electron.

Answer 9

(C) [SSC CHSL 2012] Exp: Gravitational and nuclear forces are able to provide an attractive force between two neutrons. However, nuclear forces are stronger than gravitational forces. Nuclear forces also act between neutron-proton and proton-proton.

Answer 10

(B) [SSC Stenographer 2012] Exp: A Cathode Ray is a beam of electrons in a vacuum tube travelling from the negatively charge electrode (Cathode) at one end to the positively charged electrode (anode) at the other, across a voltage difference between the electrodes. They are also called Electron Beams.

Answer 11

(C) [SSC CGL Re-Exam. 2013] Exp: When cathode rays strike a solid target of high atomic weight and high melting point such as molybdenum tungsten, etc they give rise to a highly penetrating radiations called the X-rays.

Answer 12

(B) [SSC CPO Exam. 2016] Exp: J.J. Thomson proposed that an atom possesses a spherical shape in which the positive charge is uniformly distributed. The electrons are embedded into it. This model is known is plum pudding, raisin pudding or watermelon Model.

Answer 13

(D) Exp: A. Thomson Model Plum Pudding Model B. Rutherford Model Nuclear theory C. Bohr's Model Concept of quantization of energy D. De-Broglie theory Dual Nature of Electron

Answer 14

(B) [SSC CHSL Exam. 2016] Exp: Atomic number is equal to number of protons present in nucleus. It is a characteristic of a chemical element.

Answer 15

(B) Exp: Atomic number is a whole number because it is equal to number of protons present in nucleus.

Answer 16

(B) [SSC CGL 2013] Exp: d block elements have electronic configuration (n-1)d1-10 ns0-2. Cu is d block element because it has following electronic configuration 1s2, 2s22p6, 3s23p63d10, 4s1

Answer 17

(B) Exp: Electronic configuration of calcium atom:- Ca = 2, 8, 8, 2 Electronic configuration = 1s2 2s2 2p6 3s2 3p6 4s2 Ar = 2, 8, 8 (Z = 18)

Answer 18

(B) (SSC CHSL 2016) Exp: Cr (Z = 24) - 2, 8, 13, 1 [Ne] 3s2 3p6 3d5, 4s1 Half filled orbitals are more stable than partially filled orbitals.

Answer 19

Ans (C) Exp: Isotones are the atoms in which the number of neutrons i.e., (A - Z) are equal. Thus if x is the atomic number of Y, then for 26X54 and x Y56 we have: 54 - 26 = 56 - x, x = 28

Answer 20

(A) (SSC CHSL 2016) Exp: 19K - 2, 8, 8, 1 Noble state means 8 electrons in valence shell. After removal of 1 electron K change into K+ ion. K+ - 2, 8, 8

Answer 21

(D) (SSC CHSL 2016) Exp: Atomic number of hydrogen (1H1) is 1. It has three isotopes name as protium (1H1), deuterium (1H2) and tritium (1H3).

Answer 22

(D) (SSC CHSL 2016) Exp: Atomic number of Aluminium (Z =13) is greater than that of Magnesium (Z =12). Element Atomic numbers (Z) Neon (Ne) = 10 Fluorine (F) = 9 Sodium (Na) = 11 Aluminium (Al) = 13

Answer 23

(A) (SSC CHSL 2016) Exp: Atomic number of Phosphorous (Z =15) is greater than that of Aluminium (Z =13). Element Atomic numbers (Z) Phosphorous(P) 15 Neon(Ne) 10 Magnesium(Mg) 12 Sodium(Na) 11

Answer 24

(C) (SSC CHSL 2016) Exp: Chlorine (Z=17) has higher atomic no than that of phosphorous (Z = 15). Element Atomic numbers (Z) Phosphorous (P) 15 Aluminium (Al) 13 Silicon(Si) 14 Chlorine (Cl) 17 Magnesium(Mg) 12

Answer 25

(B) (SSC CHSL 2016) Exp: Magnesium (Z =12) has greater atomic no. than that of Neon (Z = 10). Element Atomic numbers (Z) Neon (Ne) 10 Oxygen (O) 8 Magnesium (Mg) 12 Nitrogen (N) 7 Boron(B) 5

Answer 26

(B) (SSC CHSL 2016) Exp: Atomic No. of Sulphur (Z = 16) is greater than that of silicon (Z = 14). Element Atomic numbers (Z) Silicon (Si) 14 Aluminium (Al) 13 Sulphur (S) 16 Magnesium(Mg) 12 Sodium(Na) 11

Answer 27

(D) (SSC CHSL 2016) Exp: Atomic number of Bromine (Z = 35) is greater than that of Zinc (Z = 30). Element Atomic numbers (Z) Zinc (Zn) 30 Copper (Cu) 29 Iron(Fe) 26 Chromium (Cr) 24 Bromine (Br) 35

Answer 28

(C) (SSC CHSL 2016) Exp: Atomic number of Platinum (Z = 78) is greater than that of Iodine (Z = 53). Element Atomic numbers (Z) Iodine(I) 53 Silver (Ag) 47 Bromine(Br) 35 Platinum(Pt) 78 Zinc (Zn) 30

Answer 29

(C) (SSC CHSL 2016) Exp: Calcium (Z = 20) has higher atomic no. than that of potassium (Z = 19).

Answer 30

(D) (SSC CHSL 2016) Exp: Scandium (Z = 21) has greater atomic no. than that of Calcium (Z = 20). Element Atomic numbers (Z) Sulphur (S) 16 Chlorine(Cl) 17 Calcium (Ca) 20 Argon(Ar) 18 Potassium(K) 19

Answer 31

(A) (SSC CHSL 2016) Exp: Potassium (Z = 19) has higher atomic no. than that of Chlorine (Z = 17).

Answer 32

(C) (SSC CHSL 2016) Exp: Zinc (Z = 30) has higher atomic no. than that of Copper (Z = 29). Element Atomic numbers (Z) Iron(Fe) 26 Chromium(Cr) 24 Zinc (Zn) 30 Manganese (Mn) 25

Answer 33

(B) (SSC CGL 2016) Exp: Atomic No. (Z) is numerically equal to the number of protons present in the nucleus of an atom. Thus, Atomic Number (Z) = number of protons.

Answer 34

(A) (SSC CHSL 2016) Exp: Atomic Number of Sodium (Z = 11) is greater than that of Fluorine (Z = 9).

Answer 35

(B) (SSC CHSL 2016) Exp: Atomic number of Cobalt (Z = 27) is greater than that of Iron (Z = 26).

Answer 36

(B) [SSC CHSL 2015] Exp: Mass number (A) = number of protons (p) + number of neutrons (n). A = p + n or Z + n ( p = Z)

Answer 37

(D) [SSC CHSL 2010] Exp: The mass number of an atom is equal to sum of number of neutrons and number of protons present in it, which is sometimes more or sometimes equal to its atomic number.

Answer 38

(B) [SSC MTS 2008] Exp: A = 36, Z = 17 A = p + n So, n = A - p n = A - Z (Z = p) n = 36 - 17 = 19

Answer 39

(B) [SSC Stenographer 2005] Exp: Atomic weight = Atomic number (No of Protons) + No of neutrons, 18+17 = 35.

Answer 40

(C) [SSC DP SI Exam. 2014] Exp: Z = p = 92 A = 238 n = A - p = 238 - 92 = 146

Answer 41

(B) [SSC Combined Matric Level Exam. 2006] Exp: Z = 88, A = 226 Z = p = e = 88 n = A - p = 226 - 88 = 138

Answer 42

(B) (SSC CHSL 2016) Exp: Molar mass = 2 × 16 = 32 g. No. of moles = 2 Mass of 2 moles = 2 × 32 = 64 gm

Answer 43

(D) [SSC CGL 2013] Exp: The phenomenon of ejection of electrons from the surface of a metal when light of suitable frequency strikes on it. This phenomenon is known as Photoelectric effect. The emitted electrons are called photoelectrons. Cesium (Cs), Rubidium (Rb) & Potassium (K) shows Photo electric effect.

Answer 44

(C) Exp: Threshold frequency (v0): It is defined as for each metal, certain minimum frequency of light is needed to eject the electrons from the metal surface.

Answer 45

(A) Exp: Quanta are described as discrete packets of energy. In terms of light quantum is known as Photon.

Answer 46

(B) Exp: Planck's constant is represented by h. h = 6.62×10-34 J.s

Answer 47

(B) (SSC CGL 2016) Exp: E = h E = hc .... (i) c E = mc2.... (ii) hc = mc2 = h h mc p 1 p

Answer 48

(B) [SSC CGL 2015] Exp: De Broglie predicted that small particles such as electrons should show wave like properties along with particle character. The wavelength () associated with a particle of mass m and moving velocity v is given in the relationship. represents wave nature & p represents particle nature. = h h p mv p mv h = Planck's constant p = Momentum m = Mass v = Velocity

Answer 49

(B) Exp: De Broglie predicted that small particles such as electrons should show wave like properties along with particle character. The wavelength () associated with a particle of mass m and moving velocity v is given in the relationship. represents wave nature & p represents particle nature. = h h p mv p mv h = Planks constant p = Momentum m = Mass v = Velocity

Answer 50

(A) Exp: P. x > 4 h π P = mv m v. x > 4 h π v. x > 4 h πm P = change in momentum x = change in position v = change in velocity

Answer 51

(A) Exp: X-rays was discovered by Wilhelm Roentgen.

Answer 52

(B) Exp: X-Rays are used to read an old written material because they have high penetrating power. Uses of X-rays: Detection of abnormalities of the skeletal system. To detect structural deficits or cracks in metal objects. To reveal stress related changes in building materials. In examination of baggage in airports.

Answer 53

(B) Exp: Increasing order of wavelength of Electromagnetic Radiations:- Cosmic rays < Gamma rays < X-rays < U.V. rays < Visible radiation < I.R. < Microwaves < Radio waves Note: Wavelength is inversely proportional to frequency.

Answer 54

(A) Exp: In the given options, cathode rays are not electromagnetic in nature. Electromagnetic waves are waves which can travel through the vacuum of outer space. They travel with the speed of light. These are Radio waves, Micro-waves, X-rays, Gamma Rays, Infra-Red waves etc.

Answer 55

(B) Exp: Chlorophyll is present in leaves. Chlorophyll absorbs light in the red (Long wavelength) and the blue (short wavelength) region of the visible light spectrum.

Answer 56

(A) (SSC CGL 2016) Exp: The penetrating power of X-Rays is determined by the peak energy (KVp) of the voltage placed across the X-Ray tube. The higher the energy the greater the penetrating power.

Answer 57

(D) (SSC CGL 2016) Exp: The production of X-ray is a reverse process of photoelectric effect. In photoelectric effect, Photons are incident on a metal surface and electrons are produced and X-rays are produced when target metal is bombarded by electrons.

Answer 58

(A) (SSC CGL 2016) Exp: The different type of radiations are arranged in the decreasing order of frequencies or Increasing order of wavelength as: Cosmic rays, Gamma rays, X-rays, Ultraviolet radiations, Visible radiations, Infrared radiations, Microwaves and Radio waves.

Answer 59

(C) [SSC CGL Exam. 2016] Exp: Atoms of an element having same atomic number but having different mass number are known as isotopes. eg:- 1H1, 1H2, 1H3

Answer 60

(A) [SSC MTS 2013] Exp: Nuclides having same atomic number are known as Isotopes. eg:- 7N14 7N15

Answer 61

(B) (SSC CGL 2016) Exp: Atoms of an element having same atomic number but having different mass number are known as isotopes. eg:- 6C12, 6C14

Answer 62

(A) [SSC CGL Exam. 2016] Exp: Chemical properties depend on number of valence electrons. Isotopes have same number of electrons. So they have same chemical properties.

Answer 63

(A) [SSC CHSL Exam. 2015] Exp: Atoms having the same number of protons but different number of neutrons are called isotopes.

Answer 64

(C) [SSC CGL Re-Exam. 2013] Exp: Atoms of different elements have different atomic number and different number of valence electrons.

Answer 65

(C) [SSC Stenographer 2005] Exp: Atoms having equal number of neutrons but different number of Electron or Protons are called Isotones. For Example 14Si30 15P31 A = 30 31 Z = p = e = 14 15 n = A - p = 16 16

Answer 66

(C) [Expected Question] Exp: All have same mass no. but different atomic no. so they are known as Isobars.

Answer 67

(A) (SSC CHSL 2016) Exp: Isobars have same mass number but different atomic number. Eg: 14 6C, 14 7N

Answer 68

(B) Exp: Neil Bohr was the first to explain Hydrogen spectrum there are five series in Hydrogen spectrum. 1. Lyman series Ultraviolet region 2. Balmer Series Visible region 3. Paschen Series Infrared region 4. Brackett Series Infrared region 5. Pfund Series Infrared region

Answer 69

(B) Exp: Bohr's model can explain spectrum of any atom or ion having one electron only. eg:- He+, Li2+

Answer 70

(B) Exp: 0.529n2, n = 1, radius is in 10-8 cm. The value of Bohr radius of hydrogen atom is 0.529 × 10-8 cm

Answer 71

(A) Exp: Radius of nth orbit of hydrogen atom rn = r × n2

Answer 72

(C) [SSC CGL Exam. 2013] Exp: Emission spectra- It is obtained from the substances which emit light on excitation, i.e. either by heating substances on a flame or by passing electric discharge through gases at low pressure or by passing electric current through a thin filament of high melting point metal.

Answer 73

(B) Exp: According to Heisenberg's Uncertainty principle, position & velocity of an object can not be measured simultaneously with accuracy which is in contradict to Bohr's theory.

Answer 74

(C) [SSC CHSL Exam. 2010] Exp: Potential energy of the electron is negative inside any atom. The electron also has Kinetic energy which can never be -ve because in expression, there is square of velocity i.e. always +ve & it is smaller in magnitude than the magnitude of potential energy. Total energy = Kinetic energy + Potential energy = 2 1 KZe mv - 2 2 r So, total energy of electron can never be positive.

Answer 75

(D) Exp: He and Li+ both have same number of electron so spectrum of He will be similar to Li+

Answer 76

(B) Exp: If energy is absorbed, electrons goes to higher energy level from lower energy level. If energy is released, electronsdrop from a higher energy level to a lower energy level

Answer 77

(A) Exp: When electron returns to any of the lower energy levels, it emits energy. Lyman series is formed when the electron returns to the lowest energy state (K energy level) from high energy levels.

Answer 78

(B) Exp: Spectral lines for Hydrogen atomSeries Spectral region Lyman Ultraviolet Balmer Visible Paschen Infrared Brackett Infrared Pfund Infrared

Answer 79

(B) (SSC CHSL 2016) Exp: The total number of orbitals in a principal shell are n².

Answer 80

(C) [SSC CGL 2015] Exp: The mercury and sodium street lamps light up because of Atomic emission. Atomic emission occurs when a valence electron in a higher energy atomic orbital returns to a lower energy atomic orbital.

Answer 81

(D) Exp: The space or a three-dimensional region around the nucleus where there is maximum probability of finding an electron of a specific energy is called an atomic orbital.

Answer 82

(D) Exp: H= 1s1 Li = 1s2, 2s1 Be = 1s2, 2s2, B = 1s2, 2s2,2p1 S-orbital - P-orbital- Spherical dumb-bell shape

Answer 83

(B) [SSC MTS 2013] Exp: Principal Quantum number describes the shell, size of orbital and energy of orbital. Magnetic Quantum number describes the orientation of orbital. Electron spin quantum number describes the orientation of the spin of electron. Azimuthal Quantum number describes the three-dimensional shape of orbital.

Answer 84

(B) [SSC CGL Exam. 2016] Exp: = +1/2 one electron of orbital is clockwise and other electron of s-orbital is anticlockwise =-1/2

Answer 85

(B) [SSC Section Officer (Audit) 1997] or

Answer 86

(B) Exp: According to Pauli's exclusion principle - No two electrons in an atom can have the same set of four quantum numbers. or Only two electrons may exist in the same orbital and these electrons must have opposite spin.

Answer 87

(B) [SSC CGL 2002] Exp: According to Pauli's exclusion principle only two elctrons may exist in the same orbital and these electrons must have opposite spin.

Answer 88

(B) Exp: Orbital Shape s Spherical p dumb bell d double dumb bell f diffused shape

Answer 89

(A) Exp: According to Aufbau principle in the ground state of the atoms, the orbitals are filled in order of their increasing order of energy.

Answer 90

(C) Exp: According to (n + l) Rule:- for 3d, n = 3, l for d subshell = 2 (n + l) = (3 + 2) = 5 for 4s, n = 4, l for s subshell = 0 (n + l) = (4 + 0) = 4 for 4p, n = 4, l for p subshell = 1 (4 +1) = 5 Greater the (n + l) value, greater the energy of subshell. When (n + l) value is same priority is given to less value of l. So, energy order is 4s < 3d < 4p

Answer 91

(D) Exp: According to Hund's rule pairing of electrons in the orbitals belonging to the same subshell does not take place until each orbital belonging to that subshell has got one electron each.

Answer 92

(A) Exp: unpaired electrons in nitrogen atom can be explained by Hund's rule N = 2, 5 1s2 2s2 2p3

Answer 93

(B) [SSC CHSL 2014] Exp: Hydrogen 1 1H Z = p = e = 1 A = 1 n = A - p = 0 1 - 1 = 0

Answer 94

(C) (SSC CPO 2017) Exp: Neutron is a subatomic particle that does not have any electric charge. Proton has positive charge while electron has negative charge.

Answer 95

(C) (SSC CPO 2017) Exp: Atomic Mass number is equal to the sum of number of protons & neutrons. A = n + p Where A = Atomic Mass number n = no. of neutrons p = no. of protons.

Answer 96

(B) (SSC CPO 2017) Exp: Nucleus of an atom consists of proton & neutron. While electrons revolve around the nucleus in a circular paths, called as Orbits.

Answer 97

(D) (SSC CPO 2017) Exp: Molecular mass is the mass of one mole of a substance in gram.

Answer 98

(D) (SSC CPO 2017) Exp: Iodine ion (I-) is negatively charged as it is nonmetal, it gains electron to form anion. As Ca, Zn & Ag are metals so, calcium ion (Ca2+), zinc ion (Zn2+) & silver ion (Ag+) are cations.

Answer 99

(C) (SSC CPO 2017) Exp: Atomic no. is the no. of protons present in nucleus of an atom. It is represented by Z.

Answer 100

(B) (SSC CPO 2017) Exp: Cations are formed by removal of electrons. Metals generally form cations as they are electropositive elements.

Answer 101

(A) (SSC CPO 2017) Exp: Anions are formed by addition or gaining of electron. Generally non-metals form Anion as they are electronegative elements.

Answer 102

(C) (SSC CGL 2017) Exp: Metals form cation as they are electron donors. So, Aluminium, copper & zinc form cation. Aluminium ion Al3+ Copper ion Cu2+ Zinc ion Zn2+ Sulphate ion 2- SO4 So, sulphate ion is anion.

Answer 103

(B) (SSC CGL 2017) Exp: Isobars are the elements with different atomic number but same mass number. eg:- 18 Ar40, 20Ca40 Argon & Calcium has same mass number i.e. 40 but different atomic number which are 18 and 20 respectively.

Answer 104

(B) (SSC CGL 2017) Exp: Anions are formed by gaining or addition of electrons. Generally, non-metals form Anions to become stable. Cl + e- Cl- valence electrons = 7 valence electrons = 8

Answer 105

(C) (SSC CGL 2017) Exp: Goldstein discovered positively charged particles called as protons.

Answer 106

(A) [SSC MTS 2013] Exp: Radioactivity is the fission of unstable atomic nucleus. If n/p ratio is greater then nucleus will be unstable where n = no. of neutrons and p = no. of protons. Radioactivity is a phenomenon in which nuclei of certain elements undergo spontaneous disintegration.

Answer 107

(B) (SSC CHSL 2016) Exp: Units of Radioactivity - (a) Becquerel (b) Curie (c) Rutherford So according to the options becquerel is unit of radioactivity.

Answer 108

(A) [SSC CGL 2015] Exp: Radioactivity was discovered by Henri Becquerel (1895-96). For work in this field he, along with Marie Skodowska-Curie and Pierre Curie, received the 1903 Nobel Prize in Physics.

Answer 109

(D) [SSC CGL Exam, 2005] or Uranium eventually decays into a stable isotope of - (A) Radium (B) Thorium (C) Lead (D) Polonium (C) [SSC CPO Exam, 2011 Exp: Lead (Pb) is the final product due to the radioactive decay of Uranium. This can be explained by radioactive disintegration series. Atoms having atomic no. greater than 82 are always unstable.

Answer 110

(C) [SSC CPO 2007, SSC CHSL 2011] Exp: Pokhran (District Jaisalmer in Rajasthan) is a testing range of India Nuclear Programme. India tested the first underground nuclear test on 18 May 1974 in Pokhran and after this five more nuclear test occured in 11th & 13th May 1988.

Answer 111

(D) [SSC CGL Exam, 2006] or

Answer 112

(A) (SSC CHSL 2016) Exp: Radioactivity is measured by Geiger Muller counter. It is used to count charged particles emitted by a radioactive nuclei. It is based on ionisation of gases. The ionisation chamber consists of 90% argon and 10% ethyl alcohol.

Answer 113

(D) [SSC CPO 2005] Exp: Elements having atomic number greater than 82 are all radioactive but zirconium has atomic no. 40. So it's not an radioactive element.

Answer 114

(A) [SSC CHSL 2015] Exp: Fermi is the most suitable unit to express the nuclear radius, while atomic radius is measured in Angstrom. 1 Fermi = 10-15 m, 1 Angstrom = 10-10m

Answer 115

(C) [SSC CHSL 2012] Exp: In -emission, a neutron of nucleus decays into a proton and a particle (electron).

Answer 116

(C) [SSC CHSL 2014] Exp: Elements having atomic number greater than 82 are all radioactive but Aluminium has atomic no. 13 so it does not show any radioactivity.

Answer 117

(D) [SSC Steno 2014] Exp: There are 6 Noble Gases He, Ne, Ar, Kr, Xe, Rn out of these only Radon is radioactive Nobel gas.

Answer 118

(A) [SSC MTS 2013] Exp: During Gamma emission, no change takes place in radioactive element (mass or charge) Gamma rays are emitted due to secondary effects. After the emission of an alpha particle or beta particle, the nucleus is left behind in excited state. The excess of energy is released in the form of Gamma rays. Thus Gamma rays arise from energy rearrangements in the nucleus.

Answer 119

(B) (SSC CGL 2016) Exp: Elements having atomic no. greater than 82 are radioactive in nature. In the given options, Atomic Number of Uranium is 92 so, it is a radioactive element.

Answer 120

(D) [SSC Tax Asst. 2002] Exp: Elements having Atomic no greater than 82 are radioactive in Nature. Atomic number of thorium is 90, so it is radioactive.

Answer 121

(D) Exp: Elements having Atomic no greater than 82 are radioactive in Nature. Atomic no. of Cadmium is 48, so it is not radioactive.

Answer 122

(C) (SSC CHSL 2009) Exp: Lead is good absorber of radioactive radiations so radioactive samples are stored in lead boxes.

Answer 123

(A) [SSC MTS 2011] Exp: It is seen from experiment that the attractive force between two neutrons (n-n) is nearly equal to that between two protons (p-p) or between a proton and a neutron (p-n). Thus the nuclear force does not depend on the charge of the particle.

Answer 124

(C) (SSC CHSL 2016) Exp: The lightest radioactive element is tritium. It is radioactive isotope of hydrogen.

Answer 125

(C) (SSC CHSL 2016) Exp: Plutonium element does not occur in nature but can be produced artificially.

Answer 126

(B) (SSC CHSL 2016) Exp: Elements having atomic no. greater than 82 are radioactive in nature. Atomic number of Uranium is 92, so it is radioactive element.

Answer 127

(D) (SSC CHSL 2016) Exp: Radioactive elements emit a, b and g radiations. Emission of g radiation takes place after emission of a and b radiations.

Answer 128

(C) (SSC CHSL 2016) Exp: Monazite sand is an ore of thorium it is found near coastal area of Kerala. So thorium is responsible for radioactive pollution near Kerala coast.

Answer 129

(C) (SSC CAPF's SI & CISF ASI 2013) Exp: Zirconium (Z = 40) is not radioactive element

Answer 130

(C) [SSC LDC 2014] Exp: Aluminium having atomic number 13, does not exhibit natural radioactivity.

Answer 131

(B) Exp: When n/p ratio of nuclei is high, the nuclei donot lie in the stability belt and hence becomes unstable. Being unstable such nuclei undergo spontaneous radioactive disintegration.

Answer 132

(B) Exp: The nuclei having the same number of neutrons and protons are stable while the nuclei having different number of neutrons and protons are unstable. The number of neutrons (n) and protons (p) in the given nuclei are is : (A) 5B10 p = 5, n = 10 - 5 = 5, (B) 4Be10 p = 4, n = 10 - 4 = 6, (C) 7N14 p = 7, n = 14 - 7 = 7 (D) 8O16 p = 8, n = 16 - 8 = 8.

Answer 133

(D) Exp: A radioisotope first emits or particle and becomes unstable. Then it emits -rays

Answer 134

(A) Exp: The nuclei having high n/p ratio or low p/n ratio are unstable so they are highly radioactive.

Answer 135

(B) (SSC CHSL 2016) Exp: Alpha particles have small penetrating power due to relatively larger size. They are stopped by a piece of aluminium foil of 0.1 nm thickness.

Answer 136

(B) [SSC CGL 2011] Exp: Nuclear Fission type nuclear reactions produce the most harmful radiations. Products of Nuclear fission are usually unstable and radioactive in nature while products of fusion are usually stable and non-radioactive in nature.

Answer 137

(C) [SSC S. Officer (Audit) 2001] Exp: Uranium - 235 is commonly used in nuclear reactors for producing electricity in nuclear fission. Uranium is a fissile material.

Answer 138

(A) [SSC MTS 2013] Exp: The release of energy takes place because in this reaction some mass is lost, since mass of the reactants is more than the mass of the products. The mass lost is converted into energy which is released in the reaction. The energy released is calculated with the help of Einstein's mass energy relationship:- E = mc² 235U92 + 0n1 56Ba141 + 36Kr92 + 30n1 + E

Answer 139

(A) [SSC Tax Asst. 2008] Exp: Nuclear power reactor acts on the principle of nuclear fission. In nuclear reactor energy is produced by the controlled chain reaction 235U92 + 0n1 56Ba141 + 36kr92 + 30n1

Answer 140

(C) [SSC Matric Level 2002, 2011] Exp: Neutron particle is the most essential to continue the chain reaction during the fission of Uranium. After disintegration, three neutrons are produced among these two are absorbed while remaining third neutron initiates chain reaction.

Answer 141

(A) (SSC CHSL 2016) Exp: Enrico Fermi was an Italian physicist who invented nuclear reactor. Nuclear reactor is also known as an Atomic Pile or Atomic Reactor.

Answer 142

(A) [SSC CGL 2011, SSC CPO 2010] or Control rods used in the nuclear reactor are made of: (A) Fe (B) Graphite (C) Cd (D) Be (C) Exp: The function of control rods used in the nuclear reactor is to control the number of neutrons. This is achieved by using the rods of cadmium or boron as control rods which absorb the neutrons and thus control their number.

Answer 143

(C) [SSC CGL 2008] Exp: Moderator slowdown the speed of fast moving neutrons. The most commonly used moderators are Ordinary water and Graphite. The most efficient moderator is Helium. The next most efficient one is heavy water (D2O) but this is so expensive. So it is used only in research reactors.

Answer 144

(D) [SSC CHSL 2012] Exp: Moderator slowdown the speed of fast moving neutrons. The most commonly used moderators are Ordinary water and Graphite. The most efficient moderator is Helium. The next most efficient one is heavy water (D2O) but this is so expensive. So it is used only in research reactors.

Answer 145

(D) [SSC CHSL Exam, 2014] Exp: Heavy water (D2O) contains heavy isotope of hydrogen atom (Deuterium). Liquid alloy of sodium and potassium is also used as coolant: It takes away the heat to the exchanger.

Answer 146

(B) [SSC CGL 2013] Exp: In nuclear reactor neutrons are slowdown by the moderator. The most commonly used moderators are Ordinary water and Graphite.

Answer 147

(C) (SSC CHSL 2016) Exp: Alpha particles are formed after the removal of 2 electrons from helium atom. So alpha particles are just like helium nuclei.

Answer 148

(D) [SSC CGL 20015] Exp: Due to high velocity and non material character gamma rays are more penetrating than alpha, beta and X-rays.

Answer 149

(A) [SSC Section officer (Audit) 2008] Exp: Uranium 235 is used as fuel in atomic reactor.

Answer 150

(A) [SSC CGL 2011] Exp: Boron or Cadmium rod is used to absorb neutrons to control the chain reaction during nuclear fission. When these rods completely push into reactor this position is known as shutdown of nuclear reactor.

Answer 151

(B) (SSC CHSL 2016) Exp: Graphite is used as a neutron moderator in nuclear reactor. Heavy water is the best neutron moderator.

Answer 152

(D) (SSC CHSL 2016) Exp: Cathode rays are not emitted during radioactivity. A radioisotope first emits or particle and becomes unstable. Then it emits -rays

Answer 153

(A) [SSC CAPFs SI, CISF ASI & Delhi 2005] Exp: a - particles, being more massive have minimum penetrating power.

Answer 154

(B) [SSC CPO 2016] Exp: Uranium (U-235) belongs to actinium series. Actinium is also known as (4n + 3) series. 4n for Thorium series 4n + 1 for Neptunium series 4n + 2 for Uranium series 4n + 3 for Actinium series

Answer 155

(C) Exp: If an isotope bXa loses a particle, it is converted into b+1Ya. bXa b+1Y -or -1e a 0 No. of protons in X = b No. of protons in Y = b + 1 No. of neutron in X = (a - b) No. of neutrons in Y = a - (b + 1) = a - b - 1 Obviously Y has one more proton (increase of proton) and one less neutron (decrease of one neutron) than X.

Answer 156

(B) Exp: Isobars are nuclides which have same mass numbers(A) but different atomic numbers (Z). During - deacy, no changes in mass number takes place. bXa -1e0 (-particle) + b+1Ya

Answer 157

(B) Exp: When X loses and one (2He4) and two (-1e0) particles, the mass number of the daughter element is 4 units less than that of X and the atomic number is the same as that of X. bXa 2He4 + 2 -1e0 + bXa-4 Thus the daughter elements is the isotope of X.

Answer 158

(C) Exp: 4n series is that in which the mass number of all the members of the series are exactly divisible by 4. Since it is only 208 which is completely divisible by 4, Pb-208 belongs to 4n series.

Answer 159

(A) Exp: In the nuclear reactor energy is produced by the fission of U235.

Answer 160

(B) Exp: Since in nuclear reactions (B), lighter nuclei of 1H1 fuse together to form heavier helium nucleus (2He4), it is a nuclear fusion reaction. Since nuclear reactions can take place only at extremely high temperatures only (> 106 K), these reactions are known as thermo-nuclear reactions.

Answer 161

(C) Exp: Heavy water is used as moderator. The function of a moderator is to reduce the speed of fast moving neutrons and transfers the heat from the reactor.

Answer 162

(C) (SSC CGL 2016) Exp: Nuclear fusion: A nuclear reaction in which two lighter nuclei are fused together to form a heavier nuclei is called as Nuclear Fusion. Fusion reactions are also called as thermonuclear reactions. Note: Hydrogen bomb and energy of stars (Sun) are due to on Nuclear Fusion.

Answer 163

(D) [SSC Matric Level 2002] Exp: The energy of the Sun and stars is due to fusion reaction.

Answer 164

(B) Exp: In the Sun, four hydrogen atoms (protons) get fused to give one 2He4 nucleus with the emission of two positrons (+1e0). A large amount of energy is also produced. 41H1 Fusion 2He4 + 0 1 2 e + 24.64 MeV

Answer 165

(C) Exp: The radiant energy of the sun is due to the fusion of four 1H1 nuclei to form one 2He4 nucleus with the emission of two positrons (+1e0). In this reaction, a large amount of energy is also produced. 4 1H1 Fusion 2 2He4 + 0 1 2 e + 24.64 MeV

Answer 166

(C) Exp: In the Sun, four hydrogen atoms (protons) get fused to give one 2He4 nucleus with the emission of two positrons (+1e0). A large amount of energy is also produced. 41H1 Fusion 2He4 + 0 1 2 e + 24.64 MeV

Answer 167

(B) [SSC MTS 2011] Exp: First time atomic bomb was released by America at Hiroshima Japan on 6 August named Little boy (235U) and on 9th August 1945 at Nagasaki named Fatman (239Pu)

Answer 168

(D) [SSC CGL 2011] Exp: Energy produced in hydrogen bomb is due to the nuclear fusion reactions between duterium (1H2) and tritium (1H3) nuclei. This fusion gives helium nucleus (2He4) and one neutron (0n1). In this reactions, an uncontrolled amount of energy is also generated. 1H2 + 1H3 Fusion 2He4 + 0n1 + 17.6 Me V

Answer 169

(A) [SSC CGL 2005] Exp: USA (1945), USSR (1949), UK (1952), France (1960), China (1964) exploded atom bomb before India (1974).

Answer 170

(C) [SSC 2016] Exp: Hydrogen Bomb was discovered by Edward Teller. Hydrogen bomb is based on nuclear fusion. It is 1000 times more powerful than atom bomb.

Answer 171

(B) [SSC CGL 2002] Exp: Atom bomb was developed by J. Robert Openheimer. Manhattan Project was responsible for the creation of the first functioning atomic bomb.

Answer 172

(D) [SSC CGL 2011] Exp: Atomic explosion is triggered by uncontrolled chain reaction (nuclear fission).

Answer 173

(A)Exp: Little boy & Fatman atom bombs were dropped on Japan by America during second world war.

Answer 174

(D) (SSC CHSL 2016)

Answer 175

(A) Exp: The atomic bomb contains two pieces of U235 each of sub-critical mass. One piece is called wedge and the other is called target. The size of the fissile material, U235 should not be less than the critical mass.

Answer 176

(B) Exp: The large amount of energy is produced by the fission of large piece of 92U235 by the neutrons in Atom Bomb.

Answer 177

(C) [SSC Section Officer (Audit) 2001] Exp: Plutonium is formed in nuclear power reactors from uranium. Early heart pacemakers used Pu-238 as the power source.

Answer 178

(B) [SSC CGL 2010] Exp: U-235 is used in the production of Nuclear energy. In Nuclear reactor, energy is produced by the controlled chain reaction.

Answer 179

(B) [SSC CHSL Exam, 2013] Exp: Tritium (1H3) is an isotope of hydrogen. It is the lightest radioactive element.

Answer 180

(A) [SSC Steno Exam, 2014] Exp: Trombay is odd one out of given options because there is no nuclear reactor but rest of places has Nuclear reactor. Note:- Rawatbhata,Kakarapar, Kaiga & Kudan-Kulum also have nuclear reactors.

Answer 181

(C) [SSC Steno 2012] Exp: Radioactive Phosphorous - 32 is used in the treatment of skin disease.

Answer 182

(B) [SSC CGL 2010] Exp: On heating metal at temperature greater than Curie temperature metal looses it magnetic properties - Metal - Curie temperature (ºC) Fe (Iron) - 770 Co(Cobalt) - 1130 Ni (Nickel) - 358

Answer 183

(C) [SSC Section Officer 2001] Exp: Radio carbon dating - By using the half life period of 14C, it is possible to determine the age of various objects. In living material the ratio of 14C to 12C remains constant. When the tissue in an animal or plant dies. 14C decreases because the intake and utilization of 14C do not occur. Therefore in the old tissue the ratio of 14C to 12C would decrease, depending on the age of this tissue.

Answer 184

(C) Exp: Cosmic rays have neutrons (present in the upper atmosphare) convert 7N14 to radioactive 6C14. 7N14 + 0n1 (present in the cosmic rays) 6C14 (radioactive carbon) + 1H1

Answer 185

(C) (SSC CHSL 2016) Exp: Radio carbon dating - By using the half life period of 14C, it is possible to determine the age of various objects. In living material the ratio of 14C to 12C remains constant. When the tissue in an animal or plant dies. 14C decreases because the intake and utilization of 14C do not occur. Therefore in the old tissue the ratio of 14C to 12C would decrease, depending on the age of this tissue.

Answer 186

(B) (SSC CPO 2017) Exp: The main cause of energy radiated from Sun is Nuclear fusion. In the Sun, four hydrogen atoms (protons) get fused to give one 2He4 nucleus with the emission of two positrons (+1eo). A large amount of energy is produced. 41H1 fusion 2He4 + 2+1eo + 24.64 MeV.

Answer 187

(D) (SSC CPO 2017) Exp: Boron or Cadmium rod is used to absorb neutrons to control the chain reaction during nuclear fission.

Answer 188

(A) (SSC CPO 2017) Exp: Coolant is a device in nuclear reactor which is used to remove heat generated from it & transfers to electrical generators (for electricity generation) & environment. Water is used as an coolant in Nuclear Reactor.

Answer 189

(C) (SSC CPO 2017) Exp: Moderators slow down the speed of fast moving neutrons. The most commonly used moderators are Graphite & Ordinary water.

Answer 190

(A) (SSC CGL 2017) Exp: Exothermic reactions are those in which heat is released. The energy of reactants is more than the energy of products. eg:- Nuclear reactions are exothermic reactions.

Answer 191

(B) (SSC CGL 2017) Exp: The reactions in which heat is absorbed are called as endothermic reactions. eg:- CaCO3 CaO + CO2 For decomposition of CaCO3, energy is given in the form of heat & energy is absorbed.

Answer 192

(B) (SSC CHSL 2016) Exp: Removal of electrons occur in Oxidation process. eg:- Mg (s) Mg2++2e-

Answer 193

(A) (SSC CHSL 2016) Exp: Addition of H2 is a Reduction process. While Oxidation is defined as:- (a) Addition of Oxygen or electronegative element:- eg:- 2Mg(s) + O2(g) 2MgO(s) (0) (+2) Oxidation Number (b) Removal of Hydrogen:- eg:- H2S + Cl2 2HCl + S (-2) (0) Oxidation Number (c) Loss of Electrons :- eg:- Fe(s) Fe2+ + 2e- (0) (+2) Oxidation Number

Answer 194

(B) (SSC CGL 2016) Exp: The liberation of oxygen during photosynthesis is due to photolysis of water. Photolysis of water is the process of breakdown of water molecule into protons & Oxygen under the influence of light during photosynthesis reaction. 6CO +6H O 2 2 C H O +6O 6 12 6 2 Reduction chlorophyll, hv Oxidation - 2 4 4 H O H e O 2 2 In this reaction O2 is obtained from water.

Answer 195

(B) [SSC Matric Level 1999, SSC Steno 2010] Exp: When Hydrogen burns in air, then it forms water and energy is released. This is used in Hydrogen fuel. 2H2(g) + O2(g) 2H2O(g) + Energy.

Answer 196

(D) [SSC MTS Exam, - 1999] Exp: Browning of paper in old books is caused by oxidation of cellulose. This phenomenon is called as foxing (stains of Reddish brown colour).

Answer 197

(A) [SSC Steno. 2011] Exp: Oxygen has (+)ve oxidation no. only in OF2. Let the oxidation no. of O be x. then x + 2 (-1) = 0 x = +2

Answer 198

(A) Exp: The oxidation no. of Ni in K4[Ni(CN)4] is 0 Let the oxidation no. of Ni be x. then 4(+1) + x + 4 (- 1) = 0 x = 0

Answer 199

(A) Exp: The oxidation no. of sulphur in S8, S2F2 and H2S respectively are 0, +1 and -2. In homoatomic molecule (S8) oxidation no. of an element is zero. S2F2 Let the oxidation no. of S be x 2x + 2 (-1) = 0 x 1 H2S Let the oxidation no. of S be x 2 (+1) + x = 0 x -

Answer 200

(A) [SSC Const. (GD) 1999] Exp: Nitrogen shows oxidation states from -3 to +5 in various compounds. for eg: In NH3 oxidation state of Nitrogen is -3 while in HNO3 oxidation of Nitogen is +5.

Answer 201

(D) Exp: Fe3O4 Let the oxidation number of Fe be x 3x + 4 (-2) = 0 8 x 3

Answer 202

(B) Exp: K2Cr2O7 Let the oxidation number of Cr be x 2 (+1) + 2x + 7 (-2) = 0 x = +6

Answer 203

(B) (SSC CHSL 2016) Exp: In H2O2, oxidation state of oxygen is -1. Let the oxidation number of O be x 2 (+1) + 2x = 0 X = -1

Answer 204

(D) (SSC CHSL 2016) Exp: Oxidation of CO is zero. So oxidation no. of Fe in Fe(CO)5 is zero.

Answer 205

(A) [SSC CPO 2011] Exp: Vegetable oils are converted into vegetable ghee when vegetable oils are reacted with Hydrogen gas in the presence of catalyst Ni/Pd. This process is known as Hydrogenation or Reduction of vegetable oil. During this process trans fat is formed. Vegetable oil + H2 Ni Pd / Vegetable ghee or

Answer 206

(B) Exp: Vegetable oils are converted into vegetable ghee when vegetable oils are reacted with Hydrogen gas in the presence of catalyst Ni/Pd. This process is known as Hydrogenation or Reduction of vegetable oil. During this process trans fat is formed. Vegetable oil + H2 Ni Pd / Vegetable ghee Reduction is defined as:- 1. Removal of Oxygen or electro-negative element Δ 2MgO 2Mg + O2 (+2) (0) Oxidation Number 2. Addition of Hydrogen:- F2 + H2 2HF (0) (-1) Oxidation Number 3. Gain of electrons. Mg2+(s) + 2e- Mg(s) (+2) (0) Oxidation Number

Answer 207

(D) [SSC CHSL 2011] Exp: In the presence of Moisture and oxygen, oxidation occurs due to which a Reddish-Brown Layer is deposited on iron. This Reddish brown Layer on iron is called Rust. Its chemical formula is Fe2O3.xH2O. Deposition of rust on metals is called Rusting.

Answer 208

(A) [SSC Tax Asst. 2007] Exp: Rusting of iron is due to oxidation of iron. In oxidation loss of electrons or increase in oxidation no. takes place in atom. 4Fe + 3O2 Watervapour Fe2O3. x H2O

Answer 209

(D) [SSC CGL 2014] Exp: Both O2 & Water are needed for rusting to occur.Which of the following is required for the rusting of iron? (A) Oxygen and carbon dioxide (B) Oxygen and water (C) Only carbon dioxide (D) Only oxygen (B) [SSC CPO 2011] Exp: Rust is hydrated iron oxide (Fe2O3.xH2O). The presence of water and oxygen is essential for the rusting of iron. Impurities in the iron, the presence of water vapour, acids, salts and carbon dioxide hastens rusting. Pure iron does not rust in dry and carbon dioxide free air.

Answer 210

(D) [SSC MTS 2013] Exp: Rusting of iron is a chemical change. Chemical changes are the changes in which new product is formed and properties of this new product is completely different from the base substances. The product formed by the chemical change cannot be reversed in its base matter Example Rusting of Iron, curding of Milk, cooking of food, burning of candle etc.

Answer 211

(C) [SSC CGL 2014] Exp: Iron reacts with oxygen in the presence of water and air and forms rust. Water containing salt (such as sea water) cause rusting of iron faster.

Answer 212

(B) [SSC MTS 2008] Exp: Rusting of iron is a chemical process. By rusting weight of iron increases due to deposition of hydrated iron oxide layer.

Answer 213

(C) [SSC MTS 1999] Exp: The coating of thin layer of zinc on steel or iron object is known as galvansing. Galvanising process is used to protect iron from rust.

Answer 214

(A) [SSC MTS 2002] Exp: Zinc metal is used to galvanise iron to protect it from rusting.

Answer 215

(C) [SSC MTS Exam, - 2002] Exp: Aluminium metal does not rust or corrode in moist conditions. Its surface is protected by layer of aluminium oxide (Al2O3). This prevents metal comes into contact with air and oxygen.

Answer 216

(A) [SSC MTS Exam, - 2006] Exp: Zinc metal is chiefly used for galvanising iron because zinc is more reactive than iron.

Answer 217

(D) [SSC CGL, MTS 2011, 1991, 2002, 2001] Exp: The process of deposition of a layer of Zinc over iron metal is called Galvanization. Iron having layer of zinc over it known as Galvanized iron and thus iron is prevented from rusting.

Answer 218

(B) [SSC CGL Exam, 2014] Exp: Galvanization (galvanizing) is the process of applying a protective zinc coating to steel or iron, to prevent rusting. The most common method is hot-dip galvanizing, in which metal is submerged in a bath of molten zinc.

Answer 219

(A) [SSC CGL Exam, 2014] Exp: Galvanization (galvanizing) is the process of applying a protective zinc coating to steel or iron, to prevent rusting. The most common method is hot-dip galvanizing, in which metal is submerged in a bath of molten zinc.

Answer 220

(A) [SSC CGL Exam, 2011] Exp: To prevent iron from rusting Galvanization, painting and applying Grease are beneficial but annealing is done in glass. Annealing of glass is the process of slowly cooling hot glass object after they have been formed to remove internal stresses.

Answer 221

(B) (SSC CGL 2016) Exp: Potassium permanganate (KMnO4) is a powerful oxidising agent because it liberates nascent oxygen. An oxidizing agent or oxidant, gains electrons & is reduced in a chemical reaction. Oxidant is also known as the electron Acceptor. eg:- KMnO4, K2 Cr2 O7 are some examples of strong oxidizing agent.

Answer 222

(B) [SSC Matric Level 2008] Exp: Carbondioxide is an oxidising agent because in Carbondioxide, Carbon has highest oxidation no. (+4). Oxidizing Agent is normally in one of its higher possible oxidation states because it will gain electrons & is reduced it self.

Answer 223

(B) (SSC CHSL 2016) Exp: Redox reactions are those chemical reactions in which oxidation and reduction takes place simult aneausly. Zn+Cu+2 Zn +Cu +2 oxidation Reduction

Answer 224

(B) (SSC CGL 2017) Exp: Rusting is an oxidation process. The deposition of reddish brown layer of Fe2O3.xH2O on iron is called Rusting. Iron in presence of water vapour (Moisture) & oxygen form rust. 4Fe + 3O2 water vapour 2Fe2O3.xH2O

Answer 225

(A) (SSC CGL 2017) Exp: Galvanisation is a process in which coating of zinc on iron metal is done to prevent iron from rusting.

Answer 226

(B) (SSC CGL 2017) Exp: Process of gaining electrons is reduction. Reduction is defined as :- (1) Addition of Hydrogen (2) Removal of oxygen or electronegative element (3) Addition of electrons. (4) Decrease in oxidation number. eg :- Cl2+ e- 2 Cl- (0) (-1) oxidation no.

Answer 227

(A) (SSC CGL 2017) Exp: Process of loosing electrons or increase in oxidation state is called Oxidation. eg:- Mg Mg2+ + 2e- (0) (+2) (oxidation state)

Answer 228

(A) (SSC CGL 2017) Exp: Rusting is the process of rust forming on iron. Rust is a reddish brown layer of Fe2O3. xH2O. Rust is formed when iron comes in contact with oxygen & moisture (water vapours).

Answer 229

(A) (SSC CGL 2017) Exp: The process of deposition of a layer of zinc on Iron to prevent it from rusting is called Galvanization. It is one of the best method to prevent iron from corrosion or rusting.

Answer 230

(A) (SSC CGL 2017) Exp: The process of deposition of a layer of any desired metal on another material by means of electricity is called as Electroplating. It is done for decorative purpose or to prevent corrosion of metals. Eg:- copper plating, silver plating etc.

Answer 231

(D) (SSC CGL 2017) Exp: Process of deposition of reddish brown layer on iron in the presence of oxygen & moisture is called Rusting. The brown layer i.e. Fe2O3.xH2O is called rust.

Answer 232

(A) Exp: CF3COOH is the strongest acid. Electronegative atom attracts the electron density towards itself so it decreases on O atom. To compensate electron density, O atom takes the electron from H atom by releasing H+ (Proton), i.e. called acidic nature. Strong acid is an acid which completely dissociated or ionised in aqueous solution. They have high capacity to loose proton.

Answer 233

(A) Exp: Monocarboxylic acids are stronger than phenol. In carboxylate ion, the negative charge is dispersed on two electronegative oxygen atoms while in case of phenate ion, there is only one oxygen atom to disperse the negative charge. This means that there is more dispersal of negative charge in case of carboxylate ion than phenate ion. This shows that a carboxylic acid is stronger acid than phenol. Weak acid dissociates incompletely or release some H+ in solution. Weak acid has low capacity to loose proton.

Answer 234

(A) Exp: Hydrogen is most common to all acids.

Answer 235

(B) Exp: H2SO4 (Sulphuric acid) is known as king of chemicals.

Answer 236

(A) Exp: The -OH group of -COOH can be replaced by Cl using PCl5, PCl3 or SOCl2. In the given options PCl5 is correct answer.

Answer 237

(A) (SSC CGL 2016) Exp: Phenol (C6H5OH) is also known as hydroxyl benzene.

Answer 238

(C) Exp: Ammonium chloride is acidic salt because it is a salt of strong acid and weak base. HCl + NH4OH NH4Cl + H2O

Answer 239

(D) Exp: In the given options, option (D) is correct. NaHSO4 is an acidic salt because replaceable hydrogen is present in it.

Answer 240

(D) (SSC CHSL 2016) Exp: Acid turns blue litmus to Red. Note: Methylorange becomes red in acid medium phenolphthalein remains colourless in acidic medium.

Answer 241

(D) Exp: In the given options, option (D) is false. Acids are good conductor of electricity in aqueous solution because acids ionise and produce free ions.

Answer 242

(C) Exp: Sn + 4HNO3 (Conc.) H2SnO3+ 4NO2 + H2O (Stannic acid) or Sn + 4NO3 - + 2H+ 2 SnO3 - + H2O + 4NO2 In the above reaction, Sn behaves as a non-metal.

Answer 243

(C) Exp: Since Al is rendered passive when put into conc. HNO3, the acid can be stored in containers made of Al. Passive nature of Al is due to the formation of a thin layer of Al2O3 on its surface.

Answer 244

(A) Exp: Concentrated HNO3 attacks proteins of the skin, forming a yellow nitro compound with skin which is called Xantho protein.

Answer 245

(D) [SSC MTS 2006] Exp: In the given options Trichloro acetic acid is strongest acid due to maximum -I effect. As no. of electronegative atom increases, Acidic nature increases.

Answer 246

(B) [SSC MTS 2006] Exp: In the given options only carbolic acid has -OH (Hydroxyl) group. It is commonly known as phenol. Compound Molecular Formula (A) Benzoic acid C6H5COOH (B) Carbolic acid C6H5OH (C) Acetic acid CH3COOH (D) Cinnamic acid C6H5CH = CHCOOH

Answer 247

(B) [SSC CHSL 2013] Exp: Sulphuric acid is a dibasic acid because two replaceable hydrogen atoms are present. H2SO4 H+ + HSO4 - HSO4 - H++ SO4 2- O H- O - S - O - H O = = Note: Basicity of an Acid is defined as no. of replaceable hydrogen atoms present in one molecule of acid.

Answer 248

(B) (SSC CHSL 2016) Exp: The Chemical formula of Acetic acid is CH3COOH

Answer 249

(B) (SSC CGL 2016) Exp: Chemical name of vinegar is Acetic Acid or Ethanoic acid (CH3COOH). Vinegar is 5-10% dilute solution of Acetic Acid. It is used as a preservative.

Answer 250

(D) [SSC Tax Asst. 2006] or

Answer 251

(C) [SSC Tax Asst. 2007] or

Answer 252

(A) Exp: 38% of H2SO4 solution is used in lead storage battery. It works as an electrolyte.

Answer 253

(A) Exp: In the given options, Picric acid is only acid that does not contain carboxylic acid. Picric acid is used as an explosive. It is chemically 2,4,6-Trinitro phenol. OH O N2 NO2 NO2 Structure of Picric Acid

Answer 254

(A) [SSC Steno 2012] Exp: Sulphuric acid (H2SO4) is also known as 'Oil of V itr io l ' because this acid is oily and viscous in concentrated form.

Answer 255

(C) Exp: A fruity smell is produced by the reaction of C2H5OH with CH3COOH. This reaction is known as Esterification. CH3COOH+C2H5OH H CH3COOC2H5+H2O Ethylacetate (Fruity smell)

Answer 256

(A) (SSC CGL 2016) Exp: Boric Acid (H3BO3) is used in prickly heat powder to prevent excessive sweat. It is a mild Antiseptic. It is not a protonic Acid but a Lewis acid.

Answer 257

(A) (SSC CHSL 2016) Exp: Aspirin is produced from bark of willow tree. Aspirin was discovered by Felix Hoffmann.

Answer 258

(B) Exp: Aqua regia is a mixture of conc. Nitric acid (HNO3) & conc. Hydrochloric acid (HCl) in a molar ratio of 1: 3. Aquaregia is a yellow orange fuming liquid which can dissolve the noble metals such as gold & platinum. It is also known as Royal acid.

Answer 259

(D) [SSC CHSL 2016] Exp: Baking powder is a mixture of baking soda (NaHCO3) and tartaric acid. Tartaric acid is found in grapes.

Answer 260

(B) Exp: In the given options, H2SO4 is a strong dehydrating agent this is due to strong affinity for water. C12H22O11 H SO 2 4 12C+11H2O Sugar (sucrose) (absorbed by acid)

Answer 261

(B) Exp: H2SO4 is used in lead storage battery so it is known as battery acid.

Answer 262

(C) [SSC CHSL 2014] Exp: Hydrochloric acid was historically called as acidum salis, muriatic acid & spirits of salt.

Answer 263

(D) Exp: Boric acid [H3BO3 or B (OH)3] is a mild acid. It is used to make eye lotion. It is used as an antiseptic. HCl, HNO3 & H2SO4 are strong acids.

Answer 264

(C) Exp: Malic acid is found in apples and hence its name is (L. malus = apple). It is used as acidulant in soft drinks and food stuffs. It is also used as a remedy for sore throat.

Answer 265

(B) Exp: Aspirin (Acetylsalicylic acid) is prepared by heating salicyclic acid with acetyl chloride or acetic anhydride in the presence of phosphoric acid. It reduces fever. It is also used as a pain killer.

Answer 266

(A) Exp: Oxalic acid is present as potassium hydrogen oxalate in the tomatoes and spinach. Oxalic acid is used to remove iron rust stains from clothes.

Answer 267

(C) Exp: Oxalic acid is used to remove iron rust stains from clothes.

Answer 268

(D)Exp: Acetic acid is used for making vinegar. 5-10% dilute solution of acetic acid is known as vinegar. Note: 100% pure acetic acid is known as Glacial acetic acid.

Answer 269

(D) Exp: Lactic acid is the main constituent of milk that has gone sour so, lactic acid induces souring of milk.

Answer 270

(C) Exp: Citric acid is present in juices of citrus fruits such as lemons, galgals and oranges. Lemon juice contains 7- 10% Citric acid.

Answer 271

(D) Exp: Acetic acid is known as Vinegar. Acetic acid occurs in fruit juices which have become sour as result of fermentation.

Answer 272

(C) Exp: Methyl Salicylate is used in aid Sprays and ointments. It is also used in rheumatic pains. (For eg. Omnigel, Iodex, Volini gel). It is the principle constituent of Oil of wintergreen.

Answer 273

(A) (SSC CGL 2016) Exp: Bee sting contains an acidic liquid known as formic acid. Formic acid is used in the preservation of fruits, as an antiseptic, in the treatment of gout.

Answer 274

(A) [SSC MTS 2002, 1992, SSC CGL 2010] or Vinegar is (A) Diluted acetic acid (B) Glacial acetic acid (C) Glacial formic acid (D) Diluted formic acid (A) [SSC CGL 2016] Exp: Vinegar is dilute solution of 5-10% of acetic acid (CH3COOH).

Answer 275

(D) [SSC CPO 2015] Exp: Acetic acid is used for making vinegar. 5-10% dilute solution of acetic acid is known as Vinegar. Note: 100% pure acetic acid is known as Glacial acetic acid.

Answer 276

(D) [Tax Asst. 2008] Exp: Vinegar is formed by the fermentation of cane sugar. It contains acetic acid.

Answer 277

(B) [SSC Steno 2014] Exp: If some drops of conc. H2SO4 is dropped on sugar then initially it gets converted into light brown colour and then converted into black by the following chemical equation. C12 H22O11 + H2SO4 12C + 11H2O (sugar) (Conc. Sulp- (carbon) (water) huric acid) This is also the method of obtaining carbon from carbohydrate.

Answer 278

(B) [SSC Tax Asst 2007] Exp: Formic acid-Ants, Citric acid-lemon, Tartaric acid- Tamarind

Answer 279

(C) [SSC GD 2015] Exp: Carbonic acid cannot liberate the carbon dioxide from sodium bicarbonate. NaHCO3 + CH3COOH CH3COONa + CO2 + H2O NaHCO3 + HCOOH HCOONa + CO2 + H2O 2NaHCO3 + H2SO4 Na2SO4 + 2H2O + 2CO2

Answer 280

(B) [SSC CPO Exam, 2006] Exp: Sour taste of coca cola is due to the existence of phosphoric acid it is used as flavoring agent in manufacturing of soft drinks.

Answer 281

(D) Exp: Aquaregia is used to dissolve noble metals like platinum, gold etc.

Answer 282

(A) Exp: Aquaregia is a mixture of conc. HNO3 and conc. HCl in ratio 1: 3.

Answer 283

(A) (SSC CGL 2016) Exp: Citric acid is found in the juice of citrus fruits such as lemons, limes, galgals and oranges. Lemon juice contains 7-10% citric acid.

Answer 284

(A) (SSC CHSL 2016) Exp: Formic acid (HCOOH) is injected into a person's body when red ant bites.

Answer 285

(C) (SSC CGL 2016) Exp: Formic Acid is produced by red ants. It is used in treatment of gout.

Answer 286

(C) Exp: Sodium carbonate is basic salt, because it is a salt of weak acid and strong base. H2CO3 + 2NaOH Na2CO3 + 2H2O

Answer 287

(C) Exp: In the given options B(OH)3 is not a base. B(OH)3 is not a protonic acid but acts as a lewis acid by accepting electrons from a hydroxyl ion. B(OH)3+2HOH B OH H O 4 3 -

Answer 288

(C) [SSC CGL 2012] Exp: Magnesium Hydroxide is used as an antacid, it neutralize the acidity of stomach. It is called as Milk of Magnesia.

Answer 289

(B) Exp: In the given options litmus is natural indicator. Litmus is obtained from Lichens.

Answer 290

(D) [SSC Tax Asst. 2008] Exp: Litmus is obtained from Rochella lichen. Litmus solution is a natural indicator. The substances that undergo a definite colour or odour change in presence of acids and bases are called Indicators.

Answer 291

(B) Exp: pH value of human blood is 7.35 - 7.45. Blood is alkaline in nature. Human blood contains a buffer of carbonic acid (H2CO3) and bicarbonate ion 3 HCO- in order to maintain blood pH. pH value of higher than 7.8 or lower than 6.8 can lead to death.

Answer 292

(A) Exp: Pure water is neutral in nature so its pH value will

Answer 293

(C) [SSC CGL Exam, 2014] Exp: pH scale ranges from 0-14. pH scale was discovered by H. sorenson. This scale is used to identify the nature of solution, whether it is acidic, basic or neutral. for Acidic solution, pH < 7 for Basic solution, pH > 7 for Neutral solution, pH = 7

Answer 294

(B) [SSC CHSL 2013] Exp: Lemon contains citric acid so the pH of lemon Juice is expected to be less than seven. The pH level of lemon juice is 2.

Answer 295

(C) Exp: Aluminium oxide is an amphoteric oxide because it behaves as an acid in the presence of base and behaves as base in the presence of an acid. Al2O3 + 6HCl 2AlCl3 + 3H2O Al2O3 + 2NaOH + 3H2O 2NaAlO2 + 4H2O Sodium meta Aluminate

Answer 296

(A) Exp: The drying of milk of lime (white washing) is due to the action of CO2 in air. Ca(OH)2 + CO2 CaCO3+H2O

Answer 297

(B) (SSC CHSL 2016) Exp: Soda water was invented by Joseph priestly. It is also known as carbonated water. CO2 gas is also used in soda water.

Answer 298

(A) (SSC CHSL 2016) Exp: Kidney stones are composed of calcium oxalate. It is a salt of oxalic acid.

Answer 299

(A) (SSC CGL 2016) Exp: Nitric Acid does not react with gold and platinum (noble metals) Fe + 6HNO3 Fe(NO3) 3+ 3NO2 + 3H2O Cu + 4HNO3 Cu(NO3) 2 + 2NO2 + 2H2O Zn + 4HNO3 Zn(NO3) 2 + 2H2O + 2NO2

Answer 300

(A) (SSC CGL 2016) Exp: Iodex has the smell of methyl salicylate (oil of wintergreen). It is used in ointments (eq- omnigel volini gel) for treating aches, sprains and bruises.

Answer 301

(A) (SSC CPO 2017) Exp: Brine is a solution of excess salt & water (NaCl + H2O). Brine is also called as salt water.

Answer 302

(C) (SSC CPO 2017) Exp: pH scale ranges from 0-14. The degree of the acidity or the alkalinity of a solution is measured on a scale which is called as pH scale. For Acidic solution, pH value is less than 7. For Basic solution, pH value is above 7. For neutral solution, pH value is 7. Eg:- Distill water.

Answer 303

(A) (SSC CPO 2017) Exp: Sodium bicarbonate is the chemical name of Baking Soda (NaHCO3). It is used in cooking. When it is heated, it gives out CO2 which is responsible for fluffy & light texture of bread. 2 NaHCO3 (s) Na2CO3 (s) + CO2 (g) + H2O (g)

Answer 304

(C)Exp: Sodium is a pure element. Glass is a mixture of sand, lime & soda. Cement is a mixture of limestone, clay, silica & alumina. Steel is an alloy of manganese, nickel, iron chromium & carbon etc.

Answer 305

(D) (SSC CPO 2017) Exp: Yellowish brown colour of HNO3 is due to Nitrogen dioxide which is formed by partial decomposition of HNO3 acid. 4HNO3 2 H2O + 4NO2 + O2

Answer 306

(B) (SSC CPO 2017) Exp: Nature Substance 1. Acidic (a) Carbonated drink 2. Basic (b) Soap 3. Neutral (c) Distill water Carbonated drink is Acidic in nature due to presence of H2CO3 acid. Soaps are Sodium or Potassium salts of fatty acids, which provide basic nature. Distill water has no salts or impurity so it is neither acidic nor basic i.e. neutral.

Answer 307

(D) (SSC CPO 2017) Exp: Sulphuric acid is also known as 'Oil of vitriol' because this acid is oily & viscous in concentrated form.

Answer 308

(A) (SSC CPO 2017) Exp: Hydrochloric acid is also known as Muriatic acid, acidum & spirit of salt.

Answer 309

(A) (SSC CPO 2017) Exp: Chemical name of Vinegar is Acetic Acid or Ethanoic acid (CH3COOH). Vinegar is 5-10% dilute solution of Acetic acid. It is used as preservative.

Answer 310

(B) (SSC CPO 2017) Exp: Calcium Hypochlorite is bleaching powder. Its chemical formula is CaOCl2. It is used in disinfection of water & as a bleaching agent.

Answer 311

(B) (SSC CPO 2017) Exp: Leafy vegetables contain Oxalic acid & Spinach has the highest level of Oxalic acid 750 mg per 100 g. Spinach is very good source of Vitamin A.

Answer 312

(D) (SSC CPO 2017) Exp: Washing Soda is sodium carbonate decahydrate (Na2CO3.10H2O). It is disodium salt of Carbonic acid with alkaline nature.

Answer 313

(A) (SSC CPO 2017) Exp: Washing Soda is sodium carbonate decahydrate (Na2CO3.10H2O). It is disodium salt of Carbonic acid with alkaline nature.

Answer 314

(D) (SSC CPO 2017) Exp: Tartaric acid is found in tamarind, Grapes & unriped mangoes. While oxalic acid is present in Spinach.

Answer 315

(C) (SSC CPO 2017) Exp: Chemical name of quick lime is Calcium Oxide (CaO). It reacts with water to form slaked lime. CaO + H2O Ca(OH)2.

Answer 316

(B) (SSC CPO 2017) Exp: Calcium Hypochlorite is bleaching powder. Its chemical formula is CaOCl2. It is used for disinfection of water & bleaching purpose.

Answer 317

(B) (SSC CPO 2017) Exp: The antacids are basic substances which on ingestion, decrease the stomach acidity by reacting with gastric acid. eg:- Milk of Magnesia [Mg(OH2)], Al2O3 & NaHCO3 etc.

Answer 318

(A) (SSC CGL 2017) Exp: Generally, Metallic oxides are basic in nature while non metallic oxides are acidic in nature because on reacting with water they form base and acid respectively. Magnesium is only metal in given options so it will form oxide i.e. basic in nature & convert red litmus to blue. While phosphorous, Sulphur & carbon are non-metals. They will form acidic oxides.

Answer 319

(D) (SSC CGL 2017) Exp: Acid + Base Salt + water When an acid reacts with base, then water & salt are formed as product. This reaction is called as Neutralisation Reaction. eg:- NaOH + HCl NaCl + H2O (Base) (Acid) (Salt) (Water)

Answer 320

(C) (SSC CGL 2017) Exp: pH of human blood is 7.35 to 7.5. So, pH is slightly alkaline or slightly basic.

Answer 321

(B) (SSC CGL 2017) Exp: The chemical formula of sodium chloride is NaCl. It is main constituent of salt. It is also known as table salt or rock salt.

Answer 322

(A) (SSC CGL 2017) Exp: Due to presence of lactic acid in milk. Lactic acid is weak acid so, its pH value is less than 7 or slightly acidic.

Answer 323

(C) (SSC CGL 2017) Exp: Common name of CaOCl2 is bleaching powder. In presence of dilute acids, it gives nascent oxygen, so it acts as oxisidising or bleaching agent. 2CaOCl2 + H2SO4 CaCl2 + CaSO4 + 2HOCl 2HOCl 2HCl + 2[O]

Answer 324

(A) (SSC CGL 2017) Exp: Baking soda is Sodium bicarbonate (NaHCO3). It is used in baking industry because on heating it releases CO2 which makes bread spongy & fluffy. 2 NaHCO3 Na2CO3 + CO2 + H2O

Answer 325

(D) (SSC CGL 2017) Exp: Chemical formula of quicklime is CaO (calcium oxide). When it reacts with water, it forms slaked lime. CaO + H2O Ca(OH)2

Answer 326

(C) (SSC CGL 2017) Exp: Most liquids that conduct electricity are solutions of acids, bases & salts, because they contain ions

Answer 327

(A) (SSC CGL 2017) Exp: Magnesium hydroxide [Mg(OH)2] is called as Milk of Magnesia. It is used as an antacid which on ingestion, decreases the stomach acidity.

Answer 328

(C) (SSC CGL 2017) Exp: Formic acid (HCOOH) or methanoic acid is present in red ant's sting

Answer 329

(C) (SSC CGL 2017) Exp: Calcium hydroxide [Ca(OH)2] is present in lime water. It is also called as slaked lime It is formed by reaction of quick lime (CaO) & water. CaO+ H2O Ca(OH)2

Answer 330

(C) (SSC CGL 2017) Exp: Acid + Base Salt + Water When an acid reacts with base, salt & water are formed as product. This process is called as Neutralisation reaction. eg:- Ca(OH)2 + 2HCl CaCl2 + 2H2O (Base) (Acid) (Salt) (Water)

Answer 331

(D) (SSC CGL 2017) Exp: Acid + Base Salt + water When an acid reacts with base, then water & salt are formed as product. This reaction is called as Neutralisation Reaction. eg:- NaOH + HCl NaCl +H2O (Base) (Acid) (Salt) (Water)

Answer 332

(D) (SSC CGL 2017) Exp: Tartaric acid is found in bananas, grapes & tamarind. It is added to food when a sour taste is desired.

Answer 333

(A) (SSC CGL 2017) Exp: Blue vitriol is another name of CuSO4.7H2O. It is water soluble. It is blue in colour. It is used as an insecticide & fungicide.

Answer 334

(A) (SSC CGL 2017) Exp: Acetic acid is another name of vinegar. Vinegar is 5-10% dilute solution of Acetic acid It is used as preservative.

Answer 335

(D) (SSC CGL 2017) Exp: CuSO4 + Fe FeSO4 + Cu When CuSO4 reacts with iron, ferrous sulphate & copper are formed as product. This is a displacement reaction because high reactive metal (iron) displaces the copper from its salt.

Answer 336

(A) (SSC CGL 2017) Exp: The formation of crystals (solid form) from homogeneous solution is called as Crystallisation. This process is a physical change as only liquid state is converted into solid state. There is no chemical reaction

Answer 337

(B) (SSC CGL 2017) Exp: CH3COOH + NaHCO3 CH3COONa + H2O + CO2 Vinegar & Baking soda react together to form Carbon dioxide, water & sodium acetate

Answer 338

(B) (SSC CGL 2017) Exp: Chemical formula for sulphurous acid is H2SO3. It is an aqueous solution of sulphur dioxide. It is weak & unstable acid. H2O + SO2 H2SO3

Answer 339

(B) Exp: Formation of cation occurs by loss of electron. eg. Mg Mg+2 + 2e- Element/Ion No. of electrons Magnesium (Mg) 12 Magnesium ion (Mg2+) 10

Answer 340

(C) Exp: Formation of anion occurs by gain of electrons. eg. Cl + e- Cl- Element/Ion No. of electrons Chlorine atom (Cl) 17 Chloride ion (Cl-) 18

Answer 341

(A) Exp: Ionic or electrovalent bond is formed by the complete transfer of electrons from one atom to another atom Eg. Ca O.. .. Ca +2 .. O. . .. .. -2

Answer 342

(C) Exp: Ionic Solids (compounds) are generally soluble in water and other polar solvents having high dielectric constants. This is due to larger electrostatic interactions between polar solvents and ions.

Answer 343

(C)Exp: NaCl compound has ionic bond. In NaCl compound transfer of electron takes place from Na to Cl atom.— Na Cl.. .. Na + .. - . Cl. . .. .. .

Answer 344

(A) Exp: Ionic Compounds are soluble in alcohol because alcohols are polar in nature and ionic compounds are soluble in polar solvents. Ionic compounds don't conduct electricity in solid state due to absence of free ions. Ions are bound together by strong electro-static force of attraction.

Answer 345

(A) (SSC CHSL 2016) Exp: Atoms form chemical bond to reduce potential energy of system and gain stability.

Answer 346

(C) Exp: Electrons present in the highest energy level or outer most shell of an atom are called valence electrons. Only these electrons participate in chemical bonding.

Answer 347

(D) (SSC CHSL 2016) Exp: NaCl has ionic bond because there is a transfer of electron from Na atom to Cl atom takes place. Na× Cl Na × Cl

Answer 348

(B) Exp: Covalent bond is formed by mutual sharing of electrons between two or more atoms. Eg. H2 H.. H, H - H Note- Covalent bond is also known as Molecular bond.

Answer 349

(C) Exp: N2 has triple Covalent bond. N N . . . . .. . .. . N N

Answer 350

(C) Exp: Double bond occurs in C2H4

Answer 351

(C) Exp: Covalent bond is present in CHCl3 H C Cl Cl Cl

Answer 352

(D) [SSC CGL 2016] Exp: Ethylene is non-polar molecule as it has Zero dipole moment (= 0).

Answer 353

(C) Exp: CH4 (Methane) has tetrahedral structure. H C H H H

Answer 354

(D) [SSC CPO 2014] Exp: The Octet rule is not valid for BF3 molecule. In BF3 molecule B atom has 6 electrons. F B F F 6e-

Answer 355

(A) Exp: CCl4 molecule has tetrahedral geometry. Cl Cl C Cl Cl

Answer 356

(A) Exp: The Structure of Ethylene (Ethene) is linear. CH2 = CH2

Answer 357

(A) (SSC CHSL 2016) Exp: The (O-H) bond in CH3OH is Polar Covalent due to electronegativity difference between Oxygen and Hydrogen atoms.

Answer 358

(B) Exp: Alkali metals and Alkaline earth metals form ionic bond while Aluminium forms covalent bond with Cl. So AlCl3 molecule has covalent bond.

Answer 359

(B) Exp: NaOH molecule contains both ionic and covalent bond. In NaOH molecule Na has positive charge while OH has negative charge. Ionic bond is present between Na+ & OH-. Covalent bond is present between O & H atoms in OH-.

Answer 360

(D) [SSC CGL 2014] Exp: CCl4 molecule is non polar this is due to regular tetrahedral structure and dipole moment is zero.

Answer 361

(C) Exp: NH4Cl molecule has ionic, covalent and Co-ordinate bond. Ionic bond is present between NH4 + ion and Cl- ion while covalent and co-ordinate bond is present in NH4 ion.

Answer 362

(B) Exp: Bond energy values for C-C, C = C & C C are 346, 598, 813 KJ respectively. So, C C is strongest.

Answer 363

(D) [SSC 2013] Exp: Carbon tetra chloride (CCl4) is an example of a covalent molecule. Covalent bond is formed by mutual sharing of electrons between C and Cl Atoms.

Answer 364

(C) Exp: Since F-atom which is the most electronegative atom is present in (B) and (C), the correct answer will be out of these two alternatives. Since electronegativity of O atom is greater than that of C-atom, (xF - xC) is greater than (xF - xO) and hence F - C bond will be the most polar.

Answer 365

(D) Exp: We know that the Na+ ion is larger in size than Mg2+ (Na+ > Mg2+). Similary, S2- ion is also larger in size than Cl- ion (S2- > Cl-). Now MgS has smaller cation and larger anion, it would be the most covalent (Fajan's rules) and hence would be the least soluble in water.

Answer 366

(A) [SSC MTS 2014] Exp: Ethyne or Acetylene is an unsaturated hydrocarbon. It has triple bond between carbon -carbon atoms. Structure of Ethyne:- CH CH

Answer 367

(D) [SSC MTS 2014] Exp: In Covalent compounds, bond is formed between two or more nonmetals by mutual sharing of electrons. For Example: CCl 4, H2O, CO2 etc. Alkali & Alkaline Earth Metals form ionic bond.

Answer 368

(B) (SSC CHSL 2016) Exp: O2 molecule is joined by a double covalent bond. This double bond is formed due to mutual sharing of two electron pair. x x x x x x x x x x x x

Answer 369

(B) (SSC CHSL 2016) Exp: Because of regular tetrahedron structure, bond polarity is cancelled so, carbon tetrachloride (CCl4) has no dipole moment. Dipole moment can be defined as the product of the magnitude of the charge and the distance between the centres of positive and negative charge. Dipole moment (u) = charge (q) × distance of separation (r) It is expressed in debye units (D).

Answer 370

(A) (SSC CHSL 2016) Exp: P - Cl is a polar covalent bond due to higher electronegativity of chlorine than that of phosphorous.

Answer 371

(A) (SSC CHSL 2016) Exp: Covalent bond is also called Molecular bond. Covalent bond is defined as a chemical bond that involves the sharing of electron pairs between atoms. Shared electron pairs are known as bond pairs.

Answer 372

(A) (SSC CHSL 2016) Exp: Bond formed between sulphur and chlorine is polar covalent bond because chlorine is more electronegative than sulphur and mutual sharing of electrons takes place between S and Cl.

Answer 373

(B) (SSC CHSL 2016) Exp: The polar covalent bond is formed when the atoms share the electrons unequally between each other due to electronegativity difference between O & H atom. This results in partial positive and negative charges on each atom. O H H ¶- ¶+ ¶+

Answer 374

(D) (SSC CHSL 2016) Exp: Ionic and covalent character describe the nature of the bond between atoms. The lesser the difference in electronegativity between the atoms, the greater the covalent character of the bond. The greater the difference in electronegativity between the atoms, the greater the ionic character of the bond.

Answer 375

(D) (SSC CHSL 2016) Exp: N N N2 molecule has 2 lone pair of electrons. Lone pair of electron: A pair of electron in the valence shell that does not participate in chemical bond formation.

Answer 376

(D) (SSC CHSL 2016) Exp: The residual attractive or repulsive forces between molecules or atomic groups that do not arise from a covalent bond or ionic bond is called vanderwaals bond. Vanderwaals forces (bond) term is used to define intermolecular forces. These are weak forces. These forces arise due to the following type of interactions:- (i) Dispersion forces or London forces. (ii) Dipole-dipole forces (iii) Dipole - induced dipole forces.

Answer 377

(D) [SSC CGL 2013] Exp: Water has high boiling point due to presence of hydrogen bonding.

Answer 378

(A) Exp: In the given options, CH4 does not contain hydrogen bonding. Hydrogen bonding is possible when most electronegative atoms like N, O & F are present in molecule.

Answer 379

(D) Exp: In the given options, Hydrogen bond is the weakest bond. The strength of hydrogen bond ranges from 10 - 40 KJmol-1

Answer 380

(C) [SSC CPO 2016] Exp: HF has strongest hydrogen bond because hydrogen bonding takes place between hydrogen and electronegative elements (F, O, N) and F is the highest electronegative atom. H H H H H F F F F F

Answer 381

(D) Exp: The maximum number of Hydrogen bonds in a H2O molecule is 4. Oxygen atom of H2O molecule form two hydrogen bonds while two hydrogen atoms form two other hydrogen bonds.

Answer 382

(C) [SSC CHSL 2015] Exp: The Cu2+ ions are attracted towards SO4 2- ions not only by ionic interactions (electrovalent) but also by coordinate covalent bonds. The Cu2+ ions form co-ordinate covalent bonds with water as well as sulphate ions. Also hydrogen bond is present in water and sulphate ion

Answer 383

(A) Exp: In water, Oxygen is highly electronegative than sulphur. As a result, hydrogen bonding is present in H2O molecule while hydrogen bonding is almost negligible in H2S. As a result, H2O exists in liquid state and H2S exists in gaseous state.

Answer 384

(B) [SSC CGL 2012] Exp: Boiling Point of water is high due to Hydrogen bonding.

Answer 385

(A) Exp: Strength of a Hydrogen bonding, H......M increases with the increase in the electronegativity of M-atom. Out of the given atoms, Cl-does not form H-bond while the strength of H-bonding of other atoms is in the order S < N < O < F, since the electronegativity of these atoms also increases in the same order S < N < O < F 2.5 3.0 3.5 4.0

Answer 386

(C)Exp: Hydrogen bond is formed when hydrogen atom is bonded to highly electron negative atoms such as as Fluorine, Oxygen or Nitrogen. Order of strength of H-bond:- H-F > H-O > H-N

Answer 387

(A) Exp: In CO2 molecule 2 sigma bonds are present so sp hybridisation is present in CO2 molecule. O C

Answer 388

(C) Exp: Linear mixing of atomic orbitals to form equal no. of Molecular orbitals having equal energy, is called Hybridisation & the newly formed orbitals are called as Hybrid Orbitals.

Answer 389

(B) (SSC CHSL 2016) Exp: Molecular orbital (MO) Theory was developed by F. Hund R.S. Mulliken in 1932. According to this theory - The number of molecular orbitals formed is equal to the number of combining orbitals. When two atomic orbitals combine, two molecular orbitals are formed.

Answer 390

(C) (SSC CHSL 2016) Exp: Polar molecules are soluble in polar solvents while nonpolar molecules are soluble in nonpolar solvents. Benzene is a nonpolar molecule while ethyl alcohol is polar solvent so it is insoluble in ethyl alcohol.

Answer 391

(C) (SSC CHSL 2016) Exp: Ammonia has the highest solubility in water at room temperature due to hydrogen bonding

Answer 392

(A) (SSC CGL 2016) Exp: In the given options, Lead Sulphate is not soluble in water. In lead sulphate, lattice energy is greater than hydration energy.

Answer 393

(B) Exp: Molten NaCl is good Conductor of electricity is due to presence of free ions. However it does not conduct in solid state because of strong electrostatic forces between the ions. So, ions are not free.

Answer 394

(D) (SSC CGL 2017) Exp: Hydrogen bond is the weakest in nature. Hydrogen bond is formed when H atom is covalently bonded to electronegative atoms such as F, O & N.

Answer 395

(B) (SSC CHSL 2016) Exp: Periodic table was proposed by Dimitri Mendeleev (Russian Scientist)

Answer 396

(B) [SSC MTS 2008] Exp: Total number of inner transition elements is 28 in which 14 elements are lanthanoides or lanthanides (58Ce - 71Lu) and other 14 are Actinoids or Actinides (90Th - 103Lr). Note: Lanthanoids are also called rare earth elements.

Answer 397

(D) Exp: Noble gases are 2He (1st period), 10Ne (2nd period), 18Ar (3rd period) 36Kr (4th period), 54Xe (5th period) etc. Since the atomic number of the given element is 38, this element is present in 5th period and 2nd group in the periodic table

Answer 398

(A) Exp: Representative elements are s-and p-block elements. Since K and Ba are s-block elements and N is a p-block element, these are reprsentative elements. Fe is a dblock element (transition metal).

Answer 399

(C) (SSC CHSL 2016) Exp: 4th group of Modern Periodic Table has Titanium in 4th period (Ti = 22), Zirconium in 5th period(Zr = 40), Hafnium in 6th period (Hf = 72) and Rutherfordium in 7th period (Rf = 104).

Answer 400

(B) (SSC CHSL 2016) Exp: 3rd group has 4 elements - Scandium (Sc = 21) belongs to 4th period. Yittrium (Y = 39) belongs to 5th period Lanthanum (La = 57) belongs to 6th period Actinium (Ac = 89) belongs to 7th period.

Answer 401

(A) (SSC CHSL 2016) Exp: Calcium (Z = 20) is placed in 2nd group and 4th period. IInd group of periodic table is known as alkaline earth metals. It has 6 elements. These are- Beryllium (Be=4) - 2nd period Magnesium (Mg=12) - 3rd period Calcium (Ca=20) - 4th period Strontium (Sr=38) - 5th period Barium (Ba=56) - 6th period Radium (Ra=88) - 7th period

Answer 402

(B) Exp: If we look at the modern periodic table, we find that inner-transition elements have not been placed in the main body of the periodic table. These elements have been put at a separate place at the bottom of the periodic table.

Answer 403

(C) (SSC CHSL 2016) Exp: Potassium (Z = 19) is placed in 1st group and 4th period. Ist group has 7 elements these are -Hydrogen (H=1) belongs to 1st period. Lithium (Li=3) belongs to 2nd period. Sodium (Na=11) belongs to 3rd period.Potassium (K=19) belongs to 4th period.Rubidium (Rb=37) belongs to 5th period. Cesium (Cs=55) belongs to 6th period. Francium (Fr=87) belongs to 7th period.

Answer 404

(C) Exp: We know that in a period, Electronegativity increases and in a group electronegativity decreases. On this basis we write the following order of electronegativity values of the given elements (i) C < N (same period) (ii) Si < P (same period) (iii) C > Si (same group) (iv) N > P (same group).

Answer 405

(C) Exp: We know that in a peroid, Electronegativity increases and in a group electronegativity decreases. Thus on the basis we can write the relations: (i) N < O < F (same period) (ii) P < N (same group). On combining these relations we can write P < N < O < F or F > O > N > P.

Answer 406

(D) Exp: Since the size of the given species increases in the order: Fe3+ < Fe2+ < Fe, electronegativity values of these species decrease as Fe3+ > Fe2+ > Fe.

Answer 407

(C) (SSC CHSL 2016) Exp: In the given options, Arsenic has highest electronegativity. Electronegativity generally increases on moving across a period from left to right. This is due to decrease in atomic size and increases in effective nuclear charge. Electronegativity generally decreases from top to bottom in a group a as atomic size increases and the bonding electrons become away from the nucleus.

Answer 408

(B) [SSC MTS 2008] Exp: In the given options helium has highest ionization energy. This is attributed to completely filled stable configuration of Helium. 2He - 1s2 Completely filled 1s orbital

Answer 409

(C) [SSC CHSL 2013] Exp: Nitrogen has higher ionization energy than oxygen because in Nitrogen there is half filled stable configuration in 2p orbital. 7N - 1s2, 2s22p3 8O - 1s2, 2s22p4 Note: The completely filled and completely half filled subshells are stable due to symmetrical distribution of electrons and exchange energy.

Answer 410

(C) [SSC CHSL 2016] Exp: The Ionization Potential for inert gas is very high. This is attributed to the completely filled stable configurations. However, the ionisation potential decreases with increase in Atomic Number from He to Rn due to increase in size.

Answer 411

(B) [SSC CHSL 2016] Exp: In Cesium (Cs), the outermost electron is farthest from the nucleus and so minimum energy is required to remove outermost electron from the atom. Hence Cs has lowest Ionisation Potential.

Answer 412

(D) (SSC CPO 2017) Exp: Dmitri Mendeleev gave the 'Periodic Law'. According to him, the physical & chemical properties of the elements are periodic function of their Atomic Mass. After Mendeleev, Mosley gave 'Modern Periodic Law' which states that Physical & Chemical properties of the elements are periodic function of their atomic number or no. of protons.

Answer 413

(B) (SSC CPO 2017) Exp: Element Symbol Radium Ra Radon Rn Rhenium Rh Ruthenium Ru

Answer 414

(B) (SSC CPO 2017) Exp: Chemical symbol of Iron is Fe. Atomic number is 26.

Answer 415

(C) (SSC CPO 2017) Exp: On moving in period from left to right, no. of shells remains same while no. of electrons, protons & neutrons changes.

Answer 416

(A) (SSC CGL 2017) Exp: The common characteristic of the elements of the same group in the periodic table is no. of electrons in outermost shell or valence shell. eg:- H 1s1 Li 1s2, 2s1 Na 1s2,2s22p6 ,3s1 K 1s2,2s2 2p6,3s2 3p6,4s1 Rb 1s2,2s2 2p6,3s2 3p6 3d10,4s2 4p6,5s1 H, Li, Na, K & Rb are elements of same group (1st group) having one valence electron.

Answer 417

(B) (SSC CHSL 2016) Exp: Oxygen constitutes nearly half (46.6%) and silicon about one quarter (25.7%) of the total mass of the elements in the earth's crust.

Answer 418

(C) (SSC CGL 2016) Exp: The most abundant metal in earth crust is Aluminium (8.3% by weight) while iron (4.7% by weight) is second most abundant metal

Answer 419

(C) [SSC CPO 2015] Exp: Oxygen is the most abundant element on the earth crust with 46.6%.

Answer 420

(C) (SSC CGL 2016) Exp: Bridgmanite is the most abundant mineral on Earth. It makes up about 70% of the earth's lower mantle and 38% of total volume of earth. It is made up of high density magnesium iron silicate. This name is in honour of Percy Bridgman.

Answer 421

(A) Exp: Copper is found in both states free and combined. It is a transition element. Early Man first of all used copper Metal.

Answer 422

(B) [SSC MTS 2011] Exp: Gold is found in free state in nature. Gold, Platinum are noble metals.

Answer 423

(B) (SSC CHSL 2016) Exp: Haematite (Fe2O3) is main ore of iron. It is also called red oxide of iron. It contains 69.9% iron.

Answer 424

(D) (SSC CHSL 2016) Exp: Chromite is an iron chromium oxide (FeCr2O4).

Answer 425

(A) (SSC CHSL 2016) Exp: Turquoise is a hydrated phosphate of copper and aluminium. So in the given options it is an ore/mineral of copper.

Answer 426

(D) (SSC CHSL 2016) Exp: Malachite is an ore of copper. Malachite is a green copper carbonate hydroxide mineral [CuCO3.Cu (OH2)]

Answer 427

(C) (SSC CHSL 2016) Exp: Sphalerite is the major ore of Zinc. It is also known as blende or Zinc blende.

Answer 428

(C) (SSC CHSL 2016) Exp: Carnotite is a potassium uranium vandate with chemical formula K2(UO2) 2 (VO4) 2.3H2O. It is an ore of Uranium.

Answer 429

(C) (SSC CHSL 2016) Exp: Manganite is a mineral of manganese. It is composed of manganese oxide hydroxide, MnO (OH). However, main ore of managanese is pyrolusite (MnO2).

Answer 430

(D) (SSC CHSL 2016) Exp: Cinnabar (HgS) is an ore of Mercury.

Answer 431

(A) (SSC CHSL 2016) Exp: Molybdenite (MoS2) is a principle source of molybdenum. It is a sulphide mineral.

Answer 432

(C) (SSC CHSL 2016) Exp: Magnetite (Fe3O4) is an ore of Iron. It is magnetic ore of iron. It contains 72.3% iron.

Answer 433

(B) (SSC CHSL 2016) Exp: Beryl (Be3Al2Si6O18) is an ore of Beryllium. Note: Phenacite is also an ore of Beryllium.

Answer 434

(C) (SSC CHSL 2016) Exp: Borax or sodium tetraborate [Na2B4O7.10H2O] Galena or Leadsulphide [PbS] Epsom salt or Magnesium Sulphate Heptahydtrate [MgSO4.7H2O] Brimstone - It is common name of Sulphur. Galena is main ore of Lead.

Answer 435

(B) (SSC CHSL 2016) Exp: Pyrolusite (MnO2) is an ore of Manganese.

Answer 436

(A) (SSC CHSL 2016) Exp: Ilmentite is the titanium iron oxide (FeTiO3) mineral. It is the most important ore of Titanium.

Answer 437

(B) (SSC CHSL 2016) Exp: Uraninite, formerly pitchblende is an ore of uranium.

Answer 438

(C) [SSC MTS 2014] Exp: Aluminium is not found in native (free) state. It is found in combining state with different minerals. Aluminium has three principle ores Bauxite, Diaspora, cryolite. Bauxite Al2O3.2H2O, Diaspore AlO(OH), Cryolite Na3AlF6

Answer 439

(B) [SSC CGL 2015] Exp: Bauxite is Al2O3.2H2O

Answer 440

(A) [SSC CHSL 2010] Exp: Galena (PbS) and Anglesite (PbCl2) are the ores of Lead.

Answer 441

(B) [SSC CGL Exam, 2014] Exp: Magnetite is a mineral and one of the main iron ores. With the chemical formula Fe3O4, it is one of the oxides of iron.

Answer 442

(B) [SSC Steno 2011] Exp: Bauxite - Aluminium ore Lignite - A type of Coal Magnetite - Iron ore Nitrite - Ion

Answer 443

(C) [SSC CHSL Exam, 2014] Exp: Cryolite (Na3AlF6) mineral does not contain Oxygen. Calcite (CaCO3) contains Carbon, Oxygen and Calcium. Bauxite contains Aluminium, Oxygen. Na3AlF6 is sodium Hexa fluoro aluminates.

Answer 444

(D) [SSC CGL 2008] Exp: Ruby and Sapphire are the oxides of Aluminium.

Answer 445

(D) (SSC CGL 2016) Exp: In the given option, Copper is metal while Steel, Brass and Bronze are alloy. Stainless steel - Fe = 73%, Cr = 18%, Ni = 8%, carbon = low amountBrass - Cu = 60%, Zn = 40% Bronze - Cu = 88%, Sn = 12%

Answer 446

(C) (SSC CGL 2016) Exp: Bronze is an alloy of copper and tin. It consists of 88% of copper and 12% of tin. It is used in the manufacturing of doors, windows, sculptures and utensils.

Answer 447

(A) [SSC CGL 2013] Exp: German Silver contains Copper (60%), Zinc (20%) and Nickel (20%).

Answer 448

(A) [SSC CGL 2014] or Brass is made of - (A) Copper and tin (B) Tin and lead (C) Copper and Zinc (D) Copper, tin and Zinc (C) [SSC CHSL 2011] Exp: Brass is a metal alloy, made up of Copper and Zinc. The proportions of zinc and copper can be varied to create a range of brass with varying properties.

Answer 449

(C) [SSC CGL 2005] Exp: Mercury on reacting with other metals form Amalgam. For Example- Dental Amalgam (Silver-Mercury), Potassium Amalgam, Sodium Amalgam, gold Amalgam, Aluminium Amalgam etc. Mercury is used in Thermometer.

Answer 450

(B) [SSC Stenographer 2012] Exp: Mercury on reacting with other metals form Amalgam. For Example- Dental Amalgam (Silver-Mercury), Potassium Amalgam, Sodium Amalgam, gold Amalgam, Aluminium Amalgam etc. Mercury is used in Thermometer.

Answer 451

(A) [SSC LDC 2005] Or German Silver, used for making utensils is an alloy of- (A) Copper, Silver, Nickel (B) Copper, Zinc, Nickel (C) Copper, Zinc, Aluminium (D) Copper, Nickel, Aluminium (B) [SSC CPO 2007] or

Answer 452

(C) [SSC Section off. - 2007] Exp: German silver varies in composition, the percentage of the three elements ranging approximately as follows:- Copper (50% to 61.6%), Zinc (19% to 17.2%), Nickel (30% to 21.1%). The proportions are always specified in commercial alloys.

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