NEET Chemistry Gaseous State MCQs Set C

Question. The molar volume of liquid benzene (density = 0.877 g ml^–1) increases by a factor of 2750 as it vaporises at 20ºC and that of liquid toluene (density = 0.867 g ml^–1) increases by a factor of 7720 at 20ºC. A solution of benzene and toluene at 20^ºC has vapour of 46.0 torr. Find the mole fraction of benzene in the vapour above the solution
(a) 0.47
(b) 0.74
(c) 0.26
(d) None of these
Answer: B

Question. Consider the arrangement of bulbs shown below:
What is the pressure of the system when all the stopcocks are opened?
(a) 0.56 atm
(b) 2.95 atm
(c) 7.60 atm
(d) None
Answer: A

Question. The values of van der Waals constant 'a' for the gases O₂, N₂, NH₃ and CH₄ are 1.360, 1.390, 4.170 and 2.253 L2 atm mol-2 respectively. The gas which can be liquified most easily is
(a) O₂
(b) N₂
(c) NH₃
(d) CH_4.
Answer: C

Question. The temperature at which a real gas behaves like an ideal gas over a wide range of pressures is
(a) Critical temperature
(b) Boyle temperature
(c) Inversion temperature
(d) Reduced temperature
Answer: B

Question. In van der Waals equation of state for a non-ideal gas, the term that accounts for intermolecular force of attraction is
(a) (V - b)
(b) RT
(c) [p + a/V²]
(d) (RT)-1
Answer: C

Question. Non-ideal gas approaches ideal behaviour at
(a) High temperature and high pressure
(b) High temperature and low pressure
(c) Low temperature and high pressure
(d) Low temperature and low pressure.
Answer: B

Question. Which of the following is valid at absolute zero according to kinetic theory of gases ?
(a) Kinetic energy of the gas becomes zero, but the molecular motion does not become zero
(b) Kinetic energy of the gas becomes zero and the molecular motion also becomes zero
(c) Kinetic energy of the gas decreases, but doesnot becomes zero.
(d) None of the above.
Answer: B

Question. Gases deviate from ideal behaviour at high pressure. Which of the following is correct for nonideality ?
(a) At high pressure, the collisions between thegas molecules become enormous
(b) At high pressure, the gas molecules move only in one direction
(c) At high pressure, the actual volume of the molecule of gas becomes insignificant as compared to total volume of the gas
(d) At high pressure, the intermolecular interactions become significant.
Answer: D

Question. Two glass bulbs A and B are connected by a very small tube having a stop-cock. Bulb A has a volume of 100 cm3 and contained the gas; while bulb B was empty. On opening the stop-cock, the pressure fell down to 40%. The volume of the bulb B must be
(a) 75 cm³
(b) 125 cm³
(c) 150 cm³
(d) 250 cm³
Answer: C

Question. A gas cylinder contains 15 kg of butane gas at 27oC and 10 atmospeheric pressure. It was leaking and its pressure fell down to 8 atmosphere after one day. The amount of the gas leaked is
(a) 1 kg
(b) 2 kg
(c) 3kg
(d) 4 kg.
Answer: C

Question. The temperature of an ideal gas was increased by a factor of two, at constant pressure. Make the correct statement :
(a) The momentum of the gas remains unchanged
(b) The average kinetic energy increases by a factor of 2
(c) The mean free path remains constant
(d) The r.m.s. velocity increases by a factor of 2
Answer: B

Question. The mean free path of argon molecules at 25^ºC and 1 torr is (molecular diameter of argon is 2.86 Å)
(a) 8.49 × 10^–3 cm
(b) 849 × 10^–3 cm
(c) 84.9 × 10^–3 cm
(d) None of these
Answer: C

Question. Oxygen atom is two times heavier than a methane molecule. At 298 K, the average kinetic energy of a oxygen atom is
(a) Two times that of a hydrogen molecule
(b) Same as that of a hydrogen molecule
(c) Four times that of a hydrogen moelcule
(d) Half that of a hydrogen molecule.
Answer: B

Question. Under what conditions will a pure sample of an ideal gas not only exhibit a pressure of 1 atm, but also a concentration of 1 mole litre-1?
(a) At STP
(b) When V = 22.4 litres
(c) When T = 12 K
(d) Impossible under any condition.
Answer: C

Question. A weather balloon filled with hydrogen at 1 atm and 27oC has volume equal to 12,000 litres. On ascending it reaches a place where temperature is –23^oC and pressure is 0.5 atm. The volume of the balloon is
(a) 24,000 L
(b) 20,000 L
(c) 10,000 L
(d) 12,000 L.
Answer: B

Question. Two gram of H₂ diffuses from a container in 10 minutes. How many grams of oxygen would diffuse through the same container in the same time under similar conditions ?
(a) 0.5 g
(b) 4 g
(c) 6 g
(d) 8 g
Answer: A

Question. The chloride of a metal (M) contains 65.5% of chlorine. 100 mL of the vapour of the chloride of the metal at STP weigh 0.72 g. The molecular formula of the metal chloride is
(a) MCl
(b) MCl₂
(c) MCl₃
(d) MCl₄
Answer: C

Question. If 0.2 g of a gas 'X' occupies a volume of 440 mL and if 0.1 g of CO₂ gas occupied a volume of 320 mL at the same temperature and pressure, X could be
(a) O₂
(b) NO
(c) C₄H₁₀
(d) SO₂
Answer: D

Question. 10 ml of a gaseous hydrocarbon require 30 mL of oxygen for complete combustion. The hydrocarbon is
(a) C₂H₄
(b) C₂H₂
(c) C₂H₆
(d) C3H₈
Answer: A

Question. X mL of H₂ gas effuses through a hole in a container in 5 seconds. The time taken for the effusion of the same volume of the gas specified below under identical conditions is
(a) 10 second : He
(b) 20 seconds : O₂
(c) 25 seconds : CO
(d) 55 seconds : CO₂.
Answer: C

Question. One gram of hydrogen and 112 g of nitrogen are enclosed in two separate containers each of volume 5 L and at 27^oC. If the pressure of the hydrogen is 1 atm, then the pressure of nitrogen would be
(a) 16 atm
(b) 12 atm
(c) 8 atm
(d) 4 atm.
Answer: C

Question. Which of these is incorrect ?
(a) The viscosity of gases decrease with increase of temperature
(b) The viscosity of liquids decrease with increase of temperature
(c) For moderate pressure, the viscosity of a gas is found to be independent of pressure
(d) The viscosity of liquids, in general, do not increase with increase of temperature.
Answer: A

Question. 60 grams of gaseous C₂H₆ are mixed with 28 grams of carbon monoxide. The pressure of the resulting gaseous mixture is 3 atm. The partial pressure of C₂H₆ in the mixture is
(a) 3 atm
(b) 1.5 atm
(c) 1 atm
(d) 2 atm
Answer: D

Question. Consider the following statements :
1. Molecules of different gases have the same kinetic energy at a given temperature
2. The total kinetic energy for two moles of an ideal gas is equal to 3 RT.
3. The ratio of specific heat at constant pressure and the specific heat at constant volume for noble gases is 1.33.
4. The gas with a larger value of the ratio of critical temperature to critical pressure(Tc/Pc) will have larger value of excluded volume (b) Of the statements :
(a) 1, 2 and 3 are correct
(b) 2, 3 and 4 are correct
(c) 1, 3 and 4 are correct
(d) 1, 2 and 4 are correct.
Answer: D

Question. The van der Waal's equation of state is given by [P + n²a/V²](V-nb) = nRT
The ratio a/b has the dimensions of
(a) atm L^-1
(b) L atm mol^-1
(c) L atm mol^-2
(d) L mol-1.
Answer: B

Question. Which statement is false ?
(a) The average kinetic energies of molecules from samples of different "ideal" gases is the same at the same temperature
(b) The moelcules of an ideal gas are relatively far apart
(c) All molecules of an ideal gas have the same kinetic energy at constant temperature
(d) Molecules of a gas undergo many collisions with each other and with the walls of container.
Answer: C

Question. Inversion temperature of a gas is that temperature
(a) Above which no amount of pressure can liquify a gas
(b) Below which a gas cooles down if allowed to expand
(c) At which on application of pressure a gas is completely converted into liquid without having to be in equilibrium
(d) At which the distinction between a liquid and a gas disappear.
Answer: B

Question. Which one of the following statements is the correct explanation of the fact that Cp of a gas is always greater than Cv ?
(a) At constant pressure, the gas does not do any pressure-volume work on heating
(b) At constant volume, average distance between gas molecules do not change on heating
(c) At constant volume, the gas does not do any pressure-volume work on heating
(d) At constant volume, the gas does pressure volume work on heating.
Answer: C

Question. Which one of the following statements is true according to Maxwell's law of distribution of velocities in a closed system?
(a) Velocities of all gaseous molecules are same at constant temperature
(b) Fraction of molecules with higher velocities increases with the rise in temperature
(c) Fraction of molecules with higher velocities decreases with increase in temperature
(d) There will be no change in the distribution of velocities on changing the temperature.
Answer: B

Question. Which of the following statement is wrong?
(a) The average kinetic energy of the molecule of a gas depends only on the temperature
(b) The average kinetic energy of all gases is the same at the same temperature
(c) The average speed of the molecules of a gas at given temperature is proportional to the molecular mass
(d) Molecules with a low molecular mass have higher average speeds.
Answer: C

Question. Two sealed containers of the same capacity at the same temperature are filled with 44 g of H₂ gas in one and 44 g of CO₂ gas in the other. If the pressure of CO₂ in the second container is 1 atmosphere, then that of H₂ in the first container would be
(a) 1 atmosphere
(b) 0 atmosphere
(c) 22 atmospheres
(d) 44 atmospheres.
Answer: C

Question. Two flasks X and Y have capacity 1 L and 2 L respectively and each of them contains 1 mole of a gas. The temperature of the flask are so adjusted that average speed of molecules in X is twice as those in Y. The pressure in flask X would be
(a) Same as that in Y
(b) Half of that in Y
(c) Twice of that in Y
(d) 8 times of that in Y
Answer: C

Question. Collision frequency (Z) of a gas at a particular pressure
(a) Decreases with the rise in temperature
(b) Increases with the rise in temperature
(c) Decreases initially and thereafter increases
(d) None of these
Answer: B

Question. The average velocity of an ideal gas at 0oC is 0.4 ms^-1. If the temperature of gas is increased to 546oC its average velocity will be
(a) 0.8 ms^-1
(b) 1.6 ms^-1
(c) 0.346 ms^-1
(d) 0.69 ms-1.
Answer: D

Question. A box of 1L capacity is divided into two equal compartments by a thin partition which are filled with 2g H₂ and 16g CH₄ respectively. The pressure in each compartment is recorded as P atm. The total pressure when partition is removed will be
(a) P
(b) 2P
(c) P/2
(d) P/4
Answer: A

Question. Longest mean free path stands for
(a) Nitrogen (N₂)
(b) Oxygen (O₂)
(c) Hydrogen (H₂)
(d) Chlorine (Cl₂)
Answer: C

Question. By how many folds the temperature of a gas would increase when the r.m.s. velocity of gas molecules in a closed container of fixed volume is increased from 5 x 10⁴ cm s-1 to 10 x 104 cm s^–1.
(a) 0.5 times
(b) 2 times
(c) 4 times
(d) 16 times.
Answer: C

Question. Which of the following is true about gaseous state?
(a) Thermal energy = Molecular attraction
(b) Thermal energy >> Molecular attraction
(c) Thermal energy << Molecular attraction
(d) Moelcular forces >> those in liquids.
Answer: B

Question. The circulation of blood in the human body supplies oxygen and removes carbon dioxide. The concentration of oxygen and carbon dioxide is variable but on the average 100 ml of blood contains 0.02 g of O₂ and 0.08 g of CO₂. Calculate the volume of oxygen and carbon dioxide at 1 atm and body temperature (37^oC) assuming that there is 10L of blood in the human body.
(a) 2L, 4L
(b) 1.5L, 4.5L
(c) 1.59L, 4.62L
(d) 3.82L, 4.62L.
Answer: C

Question. When the pressure is expressed in atmospheres and volume in Cubic Centimetres (c.c.), then the value of R is
(a) 0.0821 litre atm. deg-1 mol-1
(b) 821 cc atm deg-1 mol-1
(c) 82.05 cc atm deg-1 mol-1
(d) None of these
Answer: B

Question. 4.0 g of argon in a bulb at temperature T K had a pressure of P. When the bulb was placed in a hotter bath at temperature of 50o more than first, 0.8 g of gas had to be removed to get the original pressure P. The original temperature is
(a) 73 K
(b) 100 K
(c) 200 K
(d) 510 K
Answer: C

Question. A molecule of gas is struck elastically by another molecule of the same gas, so that the first molecule doubles its original velocity. There has been
(a) An exchange of potential energy
(b) An exchange of kinetic energy
(c) An exchange of chemical energy
(d) No exchange of energy
Answer: B

Question. When 2 gm of a gas A is introduced into an evacuated flask kept at 25ºC, the pressure is found to be one atmosphere.If 3 gm of another gas B is then added to the same flask, the pressure increased to 1.5 atm what is the ratio of the molecules
(a) 3 : 1
(b) 4 : 1
(c) 2 : 1
(d) 1 : 4
Answer: C

Question. An evacuated glass vessel weight 50.0 g when empty, 148.0 g when filled with a liquid of density 0.98 g ml^–1 and 50.5 when filled with an ideal gas at 760 mm Hg at 300 K. Determine the molecular weight of the gas
(a) 123.15 g mol^–1
(b) 1.2315 gms mol^–1
(c) 12.315 g mol^–1
(d) 1231.5 gms mol–1
Answer: A

Question. At 27ºC the ratio of rms velocities of ozone to oxygen is
(a) √3/5
(b) √4/3
(c) √2/3
(d) 0.25
Answer: C