NEET PYQ Chemistry(Solutions) (1) Flashcards
(141 cards)
1
Q
What is the correct order of energies of molecular orbitals of N2 molecule?
A
σ1s < σ1s < σ2s < σ2s < σ2pz < (π2px = π2py) < (π2px = π2py) < σ*2pz
This order indicates the relative energy levels of molecular orbitals in N2.
2
Q
Which reaction represents disproportionation?
A
2Cu+ → Cu2+ + Cu0
Disproportionation involves a single substance being both oxidized and reduced.
3
Q
What are the correct coefficients of the reactants for the balanced equation MnO– + C O2– + H+ → Mn2+ + CO + H2O?
A
MnO– – 2, CO2– – 16, H+ – 5
Balancing redox reactions requires careful consideration of oxidation states.
4
Q
Match the following complexes with their geometries: (a) PCl5, (b) SF6, (c) BrF5, (d) BF3.
A
(a)-(iv), (b)-(iii), (c)-(i), (d)-(ii)
The geometries are trigonal bipyramidal, octahedral, square pyramidal, and trigonal planar respectively.
5
Q
In acidic medium, H2O2 changes CrO4^2- to what?
A
Cr2O7^2-
H2O2 acts as an oxidizing agent in acidic conditions.
6
Q
Which compound will have maximum ‘lone pair-lone pair’ electron repulsions?
A
ClF3
The presence of lone pairs in ClF3 leads to significant repulsion affecting its geometry.
7
Q
Which pairs of species have the same bond order?
A
CN–, CO
Bond order is a measure of the number of bonds between two atoms.
8
Q
Which reaction is a metal displacement reaction?
A
Fe + 2HCl ⟶ FeCl2 + H2↑
Metal displacement reactions involve a more reactive metal displacing a less reactive metal from its compound.
9
Q
What is the value of ΔH for the reaction 4NO2 (g) + O2 (g) → 2N2O5 (g) if ΔHr = − 111kJ?
A
- 111 kJ
The enthalpy change indicates that the reaction is exothermic.
10
Q
For a given reaction, ΔH = 35.5 kJ mol–1 and ΔS = 83.6 JK–1 mol–1. When is the reaction spontaneous?
A
T > 425 K
A reaction is spontaneous when ΔG < 0, which can occur at high temperatures given positive ΔS.
11
Q
What is the overall order of the reaction for the mechanism X2 + Y2 → 2XY?
A
1
The overall order is determined by the slow step of the reaction mechanism.
12
Q
What is the slope of the Arrhenius plot (ln k vs 1/T) for a first order reaction?
A
-Ea/R
The slope is related to the activation energy (Ea) and the gas constant (R).
13
Q
What is the electronic configuration of the central atom in K4[Fe(CN)6]?
A
t6 e0
This configuration indicates the distribution of electrons in the d orbitals of the central iron atom.
14
Q
Which geometry and magnetic behavior does [Ni(CO)4] have?
A
Tetrahedral geometry and diamagnetic
CO is a strong field ligand, leading to paired electrons and no unpaired spins.
15
Q
How many electrons can fit in the orbital for which n = 3 and l = 1?
A
6
The formula for the maximum number of electrons in an orbital is 2(2l + 1).
16
Q
What is the equilibrium constant (K) for the reaction 2NH3 + 5 O2 ⇌ 2NO + 3H2O?
A
K = K2K3/K1
The equilibrium constant for a reaction can be derived from the constants of the individual reactions.
17
Q
What is the incorrect statement regarding electron configuration?
A
The electronic configuration of N atom is 1s2 2s2 2p3
This statement is actually correct; the question may be misleading.
18
Q
What is the correct increasing order for the wavelengths of absorption in the visible region for the complexes of Co3+?
A
[Co(H2O)6]3+,[Co(en)3]3+,[Co(NH3)6]3+
Different ligands produce varying crystal field splitting, affecting absorption wavelengths.
19
Q
What is the relationship between the sizes of 5d and 4d orbitals?
A
All the five 5d orbitals are different in size compared to the respective 4d orbitals.
20
Q
How do the shapes of 4d orbitals compare to 3d orbitals?
A
All the five 4d orbitals have shapes similar to the respective 3d orbitals.
21
Q
What is true about the energy levels of 3d orbitals in a free state?
A
In an atom, all the five 3d orbitals are equal in energy in free state.
22
Q
Which orbitals have similar shapes: dxy, dyz, dzx or dx2-y2, dz2?
A
dxy, dyz, and dzx orbitals are similar to each other; and dx2-y2 and dz2 are similar to each other.
23
Q
What is the maximum volume of a container when pressure of CO2 attains its maximum value?
A
10 litre.
24
Q
What is the reaction for CH4(g) + 2O2(g) at equilibrium?
A
The equilibrium constant for the reaction is given by Kp = [CO2].
25
Which mixture will make a basic buffer?
100 mL of 0.1 M CH3COOH + 100 mL of 0.1 M NaOH.
26
What is the solubility of AgCl(s) with a solubility product of 1.6×10-10 in 0.1 M NaCl?
1.6 × 10−11 M.
27
What happens when CH4(g) or O2(g) is added at equilibrium?
It will cause a shift to the right.
28
How does the equilibrium shift for an exothermic reaction when heat is added?
The equilibrium shifts in the backward direction.
29
What is the relationship between Kp and K'p for an exothermic reaction?
Kp < K’p when temperature increases.
30
What statement about catalysts is incorrect?
The value of equilibrium constant is changed in the presence of a catalyst.
31
Which salt will precipitate last when AgNO3 is added to a solution containing equal moles of NaCl, NaBr, NaI, and Na2CrO4?
Ag2CrO4.
32
What is the stability order of carbanions?
a > c > b > d.
33
In which confirmation of ethane is there no torsional strain?
The staggered confirmation.
34
Which biphenyl is optically active?
The one with a chiral center.
35
What is the correct order of increasing reactivity of C–X bond towards nucleophile?
I < II < IV < III.
36
What does the reaction of acetone with 2-pentanone in the presence of dilute NaOH yield?
It yields a mixture of products.
37
What is the boiling point comparison between carboxylic acids and alcohols?
Carboxylic acids have higher boiling points than aldehydes, ketones, and even alcohols of comparable molecular mass.
38
What is the reason for the higher boiling points of carboxylic acids?
Formation of intermolecular H-bonding.
39
Which of the following reactions is an elimination reaction?
CH3CH2CH2Br + KOH → CH3CH = CH2 + KBr + H2O.
40
What is the incorrect statement regarding chirality?
Enantiomers are superimposable mirror images on each other.
41
What is the stability order of the following ions in aqueous solution?
V3+ < Ti3+ < Mn3+ < Cr3+.
42
Which ion has electronic configuration [Ar] 3d6?
Fe3+.
43
What is the reason for lanthanoid contraction?
Negligible screening effect of 'f' orbitals.
44
Identify the product D from zoic acid.
Product D is not specified in the provided content
## Footnote
The specific product needs to be identified from additional context or chemical reactions involving zoic acid.
45
Which represents the correct order of acidity in the given compounds?
FCH2COOH > CH3COOH > BrCH2COOH > ClCH2COOH
## Footnote
This order is based on the electron-withdrawing effects of the substituents.
46
What is the structure of the dibromo product formed from propionic acid with Br2/P?
CH2Br–CHBr–COOH
## Footnote
This indicates the positions of bromine substitutions on the propionic acid.
47
Which artificial sweetener is stable under cold conditions only?
Aspartame
## Footnote
Aspartame is known to degrade when exposed to heat.
48
Identify the non-essential amino acid from the following options.
Alanine
## Footnote
Non-essential amino acids can be synthesized by the body.
49
Which vitamin is water-soluble?
Vitamin B
## Footnote
Vitamins B and C are generally water-soluble, while others like A, D, E, and K are fat-soluble.
50
Which of the following is a non-reducing sugar?
Sucrose
## Footnote
Sucrose does not have a free aldehyde or ketone group and does not reduce other substances.
51
D(+) glucose reacts with hydroxyl amine and yields an oxime. What is the structure of the oxime?
Not specified in the provided content
## Footnote
The structure of the oxime can be derived from the glucose structure.
52
What is the correct order of the basic strength of methyl substituted amines in aqueous solution?
(CH3)3N > (CH3)2NH > CH3NH2
## Footnote
The order reflects the steric and electronic effects on basicity.
53
Which diazonium salt is expected to be the most stable?
C6H5CH2N+X–
## Footnote
Stability of diazonium salts depends on the substituents and the structure.
54
What is the correct increasing order of the basic strength for the given compounds?
III < II < I
## Footnote
This order indicates the relative basicity of the compounds based on their structures.
55
Which reaction will NOT give primary amine as the product?
CH3CONH2 —B—r2—/KO—H—→ Product
## Footnote
This reaction typically leads to secondary or tertiary amines.
56
The number of compounds/species which obey Huckel’s rule is ___
4
## Footnote
Huckel's rule states that a compound is aromatic if it has 4n + 2 π electrons.
57
Reaction of HBr with propene in the presence of peroxide gives what product?
n-propyl bromide
## Footnote
The presence of peroxide leads to anti-Markovnikov addition.
58
What are the products formed when CH3C≡CCH2CH3 is treated with O3?
CH3COOH + CH3COCH3
## Footnote
This reaction is known as ozonolysis, which cleaves the triple bond.
59
Hydrocarbon (A) reacts with bromine to form an alkyl bromide. What is (A)?
CH2 = CH2
## Footnote
Ethylene (A) undergoes bromination to form dibromo products.
60
The element expected to form the largest ion to achieve the nearest noble gas configuration is:
Na
## Footnote
Sodium readily loses an electron to achieve a stable electron configuration.
61
Which order of ionic radii is correctly represented?
O2− > F− > Na+
## Footnote
Ionic radii depend on the charge and electron configuration of the ions.
62
The correct order of atomic radii in group 13 elements is:
B < Ga < Al < Tl < In
## Footnote
This order reflects the trends in atomic size as you move down the group.
63
Which statement about diamond and graphite is correct?
Diamond is sp3 hybridized and graphite is sp2 hybridized
## Footnote
This describes the difference in bonding and structure between the two forms of carbon.
64
The stability of +1 oxidation state increases in the sequence:
Ga < In < Al < Tl
## Footnote
This trend is due to the effective nuclear charge and electron shielding.
65
The correct order of increasing electron gain enthalpy for the elements O, S, F, and Cl is:
Cl < F < O < S
## Footnote
This reflects the stability of the added electron in each element.
66
The number of Faradays required to produce 20g of calcium from molten CaCl2 is:
2
## Footnote
The calculation is based on the molar mass and the charge of calcium ions.
67
What is the standard cell potential (Eo) for a cell involving one electron at 298 K?
0.59 V
## Footnote
This value is critical for calculating the equilibrium constant.
68
What is the equilibrium constant (K) for the cell reaction given that 2.303 RT = 0.059 V at T = 298 K?
K can be calculated using the Nernst equation
## Footnote
The Nernst equation relates Eo and K.
69
What is the van't Hoff factor (i) for a dilute aqueous solution of barium hydroxide?
3
## Footnote
Barium hydroxide dissociates into three ions in solution.
70
Which statement is true if the boiling point of a 0.2 mol kg-1 solution of X in water is greater than that of an equimolar solution of Y?
Molecular mass of X is greater than the molecular mass of Y
## Footnote
This indicates that X is a non-volatile solute.
71
If the standard cell potential (Eo) for a given reaction is negative, which of the following is true?
ΔG° > 0; Keq < 1
## Footnote
A negative Eo indicates a non-spontaneous reaction.
72
What is the weight of silver displaced by a quantity of electricity that displaces 5600 ml of O2 at STP?
54.0 g
## Footnote
This is calculated using Faraday's laws of electrolysis.
73
The molecular orbital (energy) diagram for N2 shows what type of configuration?
+1 +2 0
## Footnote
This configuration indicates the relative energy levels of the molecular orbitals.
74
Which of the following reactions is a disproportionation reaction?
2 Cu+1 → Cu2 (+) + Cu0
## Footnote
Disproportionation involves the same species being oxidized and reduced.
75
What is the geometry of SF6?
Octahedral
## Footnote
SF6 has six bonding pairs of electrons.
76
What is the n-factor of MnO4–?
5
## Footnote
The n-factor is the number of moles of electrons exchanged in the reaction.
77
What is the balanced equation for the reaction involving MnO4– and CO2–?
2MnO4– + 5CO2– + 16H+ → 2Mn2+ + 10CO + 8H2O
## Footnote
This illustrates the stoichiometry of the redox reaction.
78
XeF2 has how many bond pairs and lone pairs?
2 bond pairs and 3 lone pairs
## Footnote
This leads to a linear molecular geometry.
79
What type of reaction is Cr2O3 + 2Al → Al2O3 + 2Cr?
Metal displacement reaction
## Footnote
A more reactive metal displaces a less reactive metal.
80
For a reaction to be spontaneous, what must be true about ΔG?
ΔG = -ve
## Footnote
This indicates that the reaction is thermodynamically favorable.
81
What is the relationship between activation energy (Ea) and slope in a reaction rate graph?
Slope = -Ea/R
## Footnote
This comes from the Arrhenius equation.
82
What happens to the entropy (ΔS) during the sublimation of a solid to gas?
ΔS > 0
## Footnote
This signifies an increase in disorder.
83
Zero order reactions have what characteristic regarding concentration?
Rate is independent of concentration
## Footnote
This means that the rate remains constant regardless of reactant concentration.
84
What is the order of the ligand in the spectrochemical series from weakest to strongest?
H2O < NH3 < en
## Footnote
This order affects the color and magnetic properties of complexes.
85
What is the equilibrium constant (Kp) for the reaction SrCO3(s) ⇌ SrO(s) + CO2?
Kp = PCO2 = 1.6 atm
## Footnote
This indicates the pressure of CO2 at equilibrium.
86
What defines isoelectronic pairs?
Same number of electrons
## Footnote
Example: Fe2+ and Mn2+ are not isoelectronic.
87
What is the effect of a catalyst on the equilibrium constant?
Not affected by catalyst
## Footnote
Catalysts speed up reactions without changing equilibrium.
88
What is the effect of a catalyst on the equilibrium constant?
The equilibrium constant is not affected by a catalyst at a given temperature.
## Footnote
Catalysts speed up both forward and backward reactions by the same rate.
89
What is the concentration of NaCl, NaBr, NaI, and Na2CrO4 mentioned?
1M
## Footnote
This is the concentration specified for the salts.
90
What is the total number of electrons that can fit in the 3p orbital?
2 electrons
91
What is the expression for the solubility product constant (Ksp) of Ag2CrO4?
Ksp (Ag2CrO4) = [Ag+]^2 [CrO4^2-]
92
What is the angular momentum of an electron in a 'd' orbital?
L = l(l + 1)h
93
What is the Ksp value for AgI?
8.3 × 10^–17
94
What is the Ksp value for AgCl?
1.8 × 10^–10
95
What is the equilibrium expression for the reaction N2 + 3H2 ⇌ 2NH3?
K1 = [NH3]^2 / ([N2][H2]^3)
96
What is the pH of a solution made from a salt of weak acid and weak base?
pH = 0.5 [pKw + pKa - pKb]
97
What is the calculated pH when pKa is 4.77 and pKb is 3.27?
pH = 7.75
98
What is the product of the reaction CH3COOH + NaOH?
CH3COONa + H2O
99
Is 4-Ethyl-3-propyl hex-1-ene an aromatic compound?
No, it is not an aromatic compound as it is non-planar.
100
What is the order of stability for tautomeric compounds III > II > I based on?
The tautomer III has the highest stability due to conjugation and hydrogen bonding.
101
What is the Ksp expression for AgBr?
Ksp (AgBr) = [Ag+][Br-]
102
What occurs if sp2 hybrid carbon is attached to sp3 hybrid carbon with α-H?
Hyperconjugation occurs.
103
What happens to the equilibrium constant for an exothermic reaction with increased temperature?
The equilibrium constant decreases.
104
What is the reaction type when CH3CH2CH2Br reacts with KOH to form CH3CH=CH2?
Elimination reaction
105
What is the order of basic strength for the given compounds?
FCH2COOH > ClCH2COOH > BrCH2COOH > CH3COOH
106
What is the significance of Huckel's rule?
Huckel's rule states that (4n + 2) electrons indicate aromaticity.
107
What is the most stable oxidation state for chromium?
+3 oxidation state
108
What is the empirical formula derived from 78% carbon and 22% hydrogen?
CH3
109
What is the number of moles of CO2 produced from 0.04 moles of CaCO3?
0.04 moles
110
What type of acid is phosphoric acid?
Phosphoric acid (Phosphonic acid) H3PO3 is dibasic.
111
What is the effect of adding acetone to ethanol on vapor pressure?
It causes an increase in observed vapor pressure.
112
What is the reactivity order for substituted amines based on basic strength?
C6H5CH2N+X– > CH3CH2N+X– > CH3N+X– > C2H5N+X–
113
What is the melting point trend along the 3d series?
Melting point increases up to Cr and then decreases.
114
What is the effect of electronegativity on the stability of carbanions?
Higher electronegativity leads to higher stability of carbanions.
115
What is the stability order of the 3d transition metals based on unpaired electrons?
Cr3+ > Fe3+ > Ni2+
116
What is the relationship of ionic radii to effective nuclear charge?
More effective nuclear charge leads to smaller ionic radii.
117
What type of reaction is Williamson Synthesis?
It is a type of substitution reaction.
118
What is the bonding characteristic of carboxylic acids that increases their boiling point?
Intermolecular hydrogen bonding
119
What is the formula for the compound formed by Mg and an element X with a valency of 3?
Mg3X2
120
What is the atomic radius trend in group 13 elements?
B < Ga < Al < In < Tl
121
What is the significance of the inert pair effect?
It increases stability down the group.
122
What is the role of d-electrons in the atomic radius of Ga compared to Al?
They do not shield the nucleus effectively, leading to a smaller radius.
123
What is the result of the reaction of acetone with ethanol?
Positive deviation from Raoult’s law.
124
What is the empirical formula?
It is the simplest whole number ratio of each type of atoms present in a compound.
## Footnote
The empirical formula provides a way to represent the composition of a compound without specifying the actual number of atoms in a molecule.
125
What is Raoult’s law?
It states that the vapor pressure of a solvent in a solution is directly proportional to the mole fraction of the solvent in the solution.
## Footnote
This law is used to understand how the addition of a solute affects the vapor pressure of a solvent.
126
What happens when acetone is added to pure ethanol?
It causes breaking of some H-bonds, leading to an increase in observed vapor pressure.
## Footnote
This interaction illustrates the concept of negative deviation from Raoult's law.
127
What type of azeotrope is formed by solutions showing negative deviation from Raoult's law?
Maximum boiling azeotrope.
## Footnote
Azeotropes are mixtures that have a constant boiling point and composition throughout distillation.
128
What is the dissociation equation for Ba(OH)2 in solution?
Ba(OH)2 → Ba²⁺(aq) + 2OH⁻(aq)
## Footnote
Ba(OH)2 is a strong electrolyte, leading to complete dissociation in solution.
129
What is the Van't Hoff factor for a solution where the total number of ions present is 3?
i = 3
## Footnote
The Van't Hoff factor indicates the number of particles a solute dissociates into in solution.
130
What is the relationship for elevation in boiling point?
ΔTb = i Kb m or ΔTb ∝ i
## Footnote
This relationship helps determine how much the boiling point of a solution will increase based on solute concentration and dissociation.
131
For the liberation of O2, what is the required reaction?
MnO4⁻ + 4H2O → Mn²⁺ + H⁺ + O2
## Footnote
This reaction is part of the process in electrochemical cells where oxygen is generated.
132
What indicates that a reaction is spontaneous in terms of cell potential (Eo)?
Eo must be positive.
## Footnote
A positive Eo indicates that the reaction can occur without external energy input.
133
Calculate the cell potential (Eo) given Eo(MnO4/Mn²⁺) = 1.510 V and Eo(H2O/O2) = -1.223 V.
Eo = 1.510 + (-1.223) = 0.287 V
## Footnote
This calculation is crucial for understanding the driving force of the electrochemical reactions.
134
What is the limiting molar conductivity of CH3COOH?
400
## Footnote
The limiting molar conductivity is important for understanding the conductivity behavior of the acid in solution.
135
How is the acid dissociation constant (Ka) calculated for CH3COOH with α = 0.05?
Ka = Cα² = 0.007 (0.05)² = 1.75 × 10⁻⁵
## Footnote
This formula relates the concentration of the acid and the degree of dissociation to the strength of the acid.
136
What is the formula relating equivalent current to Faradays?
Equivalent = W × nF / MM
## Footnote
This formula relates the amount of substance transformed during an electrochemical reaction to the charge passed.
137
What is the equation for cell potential (Ecell) at equilibrium?
Ecell = Eo - 0.059 log Q / n
## Footnote
This equation is used to calculate the cell potential based on the reaction quotient at non-standard conditions.
138
What does ΔGo represent in thermodynamics?
ΔGo = -nFEo
## Footnote
This equation relates Gibbs free energy change to the cell potential and the number of moles of electrons transferred.
139
What is the implication of ΔGo being positive?
ΔGo > 0 indicates a non-spontaneous reaction.
## Footnote
This means that the reaction will not occur under standard conditions without external energy.
140
What is the relationship between the equivalents of Ag and O2 in a reaction?
eqts of Ag = eqts of O2
## Footnote
This relationship is important for stoichiometric calculations in redox reactions.
141
What is the value of w if w = 5.6 and the equivalent weight is 108 g?
w = 108 g
## Footnote
This calculation is important for determining the amount of substance in a given reaction.
