Section 1 Flashcards
(26 cards)
Solutions which distil without change in composition are called
A. ideal
B. saturated
C. supersaturated
D. azeotropic
D
Gases having same reduced temperatures and reduced pressures
A. deviate from ideal gas behaviour to the same degree.
B. have nearly the same compressibility factor.
C. both (a) and (b).
D. neither (a) nor (b).
C
Which of the following is not a unit of pressure ?
A. Torr
B. Newton/m2
C. Parsec
D. Ata, bar or pascal
B
parsec = ~ equal to 3.26 light-years or 206,265 AU i.e. 30.9 trillion km
The evaporation of aqueous solution of sugar causes its molarity to
A. decrease.
B. increase.
C. remain unchanged.
D. either (a) or (b); depends on the concentration of the solution.
B
Molarity is defined as the moles of solute per liter of sol’n
Evaporation removes water (solvent) from the solution.
The amount of solute (sugar) stays the same.
One Newton is equal to dynes.
A. 10^2
B. 10^3
C. 10^4
D. 10^5
D
A very dilute solution is prepared by dissolving ‘x1’ mole of solute in ‘x2’ mole of a solvent. The mole fraction of solute is approximately equal to
A. x1/x2
B. x2/x1
C. 1 - (x1/x2)
D. 1/x2
A
In a very dilute solution, x2 (the number of solvent molecules) is much greater than x1 (the number of solute molecules).
Because of this large difference, when we approximate, we can often neglect x1 compared to x2.
An ideal gas can be liquified, because
A. its molecular size is very small.
B. its critical temperature is more than 0°C.
C. forces operative between its molecules are negligible.
D. it gets solidified directly without becoming liquid.
C
An ideal gas is a theoretical concept where the molecules are assumed to have negligible size and no attractive forces between them. Due to the absence of these attractive forces, even if the temperature is lowered, the molecules wouldn’t be held close enough to form a liquid.
The rate of material is zero in case of a steady state system.
A. accumulation
B. production
C. input
D. generation
A
Accumulation refers to the buildup of material within the system
If the rate of accumulation is zero, it signifies that the amount of material entering the system is equal to the amount leaving it.
A metal oxide is reduced by heating it in a stream of hydrogen. After complete reduction, it is found that 3.15 gm of the oxide has yielded 1.05 gm of the metal. It may be inferred that the
A. atomic weight of the metal is 4.
B. equivalent weight of the metal is 4.
C. atomic weight of the metal is 2.
D. equivalent weight of the metal is 8.
B
Molar heat capacity of water in equilibrium with ice at constant pressure is
A. 0
B. ∞
C. 1
D. none of these
B
the amt of HE req’d to raise temp of 1mol of a subs by 1K at constant P.
even though you’re adding heat, the temperature remains constant. As the heat capacity is defined as the amount of heat required to raise the temperature by 1 Kelvin, with a constant temperature and a non-zero amount of heat added, the molar heat capacity approaches infinity mathematically.
If pH value of a solution is 8, then its pOH value will be
A. 6
B. 1
C. 7
D. 10
A
The sum of pH and pOH in such solutions is always equal to 14.
pH and pOH represent the negative logarithm of the concentration of hydrogen (H+) and hydroxide (OH-) ions, respectively.
The chemical nature of an element is independent of
A. its atomic number.
B. the number of protons or electrons present in it.
C. the number of neutrons present in it.
D. none of these.
C
The heat change for the reaction, C(s) + 2S(s) → CS2(l), is 104.2 kJ. It represents the heat of
A. formation
B. solution
C. combustion
D. fusion
A
Heat of formation refers to the enthalpy change when one mole of a substance is formed from its constituent elements in their standard states.
A sample of well water contains 140 gm/m3 Ca2+ ions and 345 gm/m3 Na+ ions. The hardness of the sample of water, expressed in terms of equivalent CaCO3 in gm/m3 is (assuming atomic masses of Ca :40, Na : 23, C : 12, O : 16)
A. 350
B. 485
C. 140
D. 345
A
Assuming that CO2 obeys perfect gas law, calculate the density of CO2 (in kg/m3) at 263°C and 2 atm.
A. 1
B. 2
C. 3
D. 4
Atomic mass of ca 40.
Molecular weight of caco3 is 100.
Therefore 40gms of ca = 100 gm of caco3.
Then 140gms of ca = ? gm of caco3.
By simplifying that 100*140 / 40.
Weight of caco3 = 350.
B
Ideal gas relation is expressed as PV =nRT; n= mass/Molecular weight).
PV=nRT ;n=PV/RT ; P=2 atm, 22.4 L/mole, 0.08205 L-atm/mole-K; T=263+273
n= 0.98; mwCO2= 44kg/mole.
Density = mass/volume;
Mass = nMW = 0.98(44kg/mole) = 43.43 kg/mole.
Density = 43.43/ 22.4 L/mole = 1,98 kg/liter.
One micron is equal to
A. 10-4 mm
B. 10-4 cm
C. 10-6 m
D. both(b)&(c)
C
Heat capacity of air can be approximately expressed as, Cp = 26.693 + 7.365 x10-3 T, where, Cp is in J/mole.K and T is in K. The heat given off by 1 mole of air when cooled at atmospheric pressure from 500°C to - 100°C is
A. 10.73 kJ
B. 16.15 kJ
C. 18.11 kJ
D. 18.33 kJ
C
Heat given off by the 1 mole of air is equal to the change in enthalpy of the air during the cooling.
DH = integration (CpDT) limits from the 773.15K to 173.15K.
Heat given off Q = DH = 18.11kJ.
Gases diffuse faster compared to liquids because of the reason that the liquid molecules
A. are held together by stronger inter-molecular forces.
B. move faster.
C. have no definite shape.
D. are heavier
A
In gases, the molecules are much farther apart and experience weaker IMF
Equal masses of CH4 and H2 are mixed in an empty container. The partial pressure of hydrogen in this container expressed as the fraction of total pressure is
A. 1/9
B. 8/9
C. 1/2
D. 5/9
B
Assume 100g of H2 and 100g of CH4.
Moles of H2=m/Mwt = 100/2 = 50 moles,
Moles ofCH4=100/16 = 6.25 moles.
Total moles = 56.25 moles.
mole fraction of H2 y = 50/56.25 = 0.8 = 8/9.
Dalton’s low p = y*P.
At atmospheric pressuer 1atm.
p=8/9 * 1 = 8/9 atm.
Which of the following is not a colligative property ?
A. Osmotic pressure
B. Depression of freezing point
C. Lowering of vapor pressure
D. none of these.
D
Colligative properties depend on the concentration of solute particles in a solution, not on the identity of the solute itself.
Colligative properties include vapor pressure lowering, boiling point elevation, freezing point depression, and osmotic pressure.
Atoms of the same element, but of different masses are called
A. isobars
B. isotones
C. isotopes
D. none of these
C
If pH value of an acidic solution is decreased from 5 to 2, then the increase in its hydrogen ion concentration is times.
A. 10
B. 100
C. 1000
D. 10000
C
-log[H+] = 5 => H+ = 0.00001.
-LOG[H+] = 2 => H+ = 0.01.
AS ASKED CONCENTRATION OF INCREASE IN H+ IONS IS FOUND OUT :
0.01/0.0001 = 1000.
Kopp’s rule is concerned with the calculation of
A. thermal conductivity.
B. heat capacity.
C. viscosity.
D. surface tension.
B
Kopp’s rule is an estimation method used to approximate the heat capacity of a compound based on the heat capacities of its constituent elements. It applies primarily to solids and, to a lesser extent, liquids. It’s not typically used for thermal conductivity, viscosity, or surface tension.
