NEET Chemistry Gaseous State MCQs Set B

Question. Energy of all molecules of a monoatomic gas having a volume V and pressure P is (3/2)PV. The total translational kinetic energy of all molecules of a diatomic gas as the same volume and pressure is:
a. (1/2) PV
b. (3/2) PV
c. (5/2) PV
d. 3 PV
Answer : B

Question. If the Van der Waal’s parameters op two gases are given as:

Then which of the following statement is/are correct?
a. Critical volume of A < critical volume of B
b. Critical pressure of A < critical pressure at B
c. Critical temperature of A > critical temperature of B
d. None of the above
Answer : B, C

Question. Select the correct statements:
a. Gases having their temperature above their Boyle’s temperature show compressibility factor Z > l
b. Gases having their temperature below their Boyle’s temperature show Z < 1 in low pressure range
c. Boyle’s temperature of He is more than H₂
d. Boyle’s temperature of NH2 is more than H₂
Answer : A, B, C

Question. At standard temperature and pressure the density of a gas is 1.3 gm/ m³ and the speed of the sound in gas is 330 m/sec. Then the degree of freedom of the gas will be:
a. 3
b. 4
c. 5
d. 6
Answer : C

Question. Which of the following statement is/are true?
a. The ratio of the average speed to the rms speed is independent of temperature
b. The square of the mean speed of molecules is equal to the mean squared speed at a certain temperature
c. Mean kinetic energy of gas molecules at any given temperature is independent of the mean speed
d. The difference between rms speed and average speed at any temperature for different gases diminishes as large, and yet larger molar masses are considered
Answer : A, C, D

Question. Which of the following statements are true regarding the kinetic theory of gases?
a. The pressure of the gas is directly proportional to the average speed of the molecules
b. The root mean square speed of the molecules is directly proportional to the pressure
c. The rate of diffusion is directly proportional to average speed of the molecules
d. The average kinetic energy per molecule is directly proportional to the absolute temperature
Answer : C, D

Question. For a jar containing H₂ and He gases which of the following statements are correct?
a. The molecules of both gases have same average translational kinetic energy
b. The molecules of both gases have same average energy
c. Hydrogen molecules have greater average energy than the helium molecules
d. The molecules of both gases have same average speed
Answer : A, C

Question. A partition divided a container having insulated walls into two compartment I and II. The same gas fills the two compartments. The ratio of the number of molecules in compartments I and II is not equal to:
a. 1 : 16
b. 6 : 1
c. 4 : 1
d. 1 : 4
Answer : A, B, C

Question. Consider a collision between an oxygen molecule and a hydrogen molecule in mixture of oxygen and hydrogen, kept at room temperature. Which of the following are possible?
a. The kinetic energies of both the molecules shall increases
b. The kinetic energy of both the molecules shall decreases
c. The kinetic energy of the oxygen molecule increases and that of the hydrogen molecule decreases
d. The kinetic energy of the hydrogen molecule increases and that of the oxygen molecule decreases
Answer : C, D

Question. The average translational energy and the rms speed of the molecules in a sample of oxygen gas at 300 K are 6.21×10⁻²¹ J and 484 m/s respectively. Assuming ideal gas behaviour, the corresponding values at 600 K are not nearly:
a. 12.42 x 10^-21 J,968m/s
b. 8.78 x 10^-21 J,684m/s
c. 6.21 x 10^-21 J,968m/s
d. 12.42 x 10^-21 J, 684m/s
Answer : A, B, C

Question. Two identical containers A and B have friction ales pistons. They contain the same volume of an ideal gas at the same temperature. The mass of the gas in A is m_A and that in B is m_B. The gas in each cylinder is now allowed to expand isothermally to double the initial volume. The change in pressure in A and B are found to be ΔP and 1.5ΔP respectively. Which of the following will not be true?
a. 4m_A = 9m_B
b. 2m_A = 3m_B
c. 3m_A = 2m_B
d. 9m_A = 4m_B
Answer : A, B, D

Question. According to kinetic theory of gases, 0K is that temperature at which?
a. pressure of ideal gas is zero
b. volume of ideal gas is zero
c. internal energy of ideal is zero
d. ideal gas liquefies
Answer : A, B, C

Question. From the following statements concerning ideal gas at any given temperature T, select the correct one (s):
a. The coefficient of volume expansion at constant pressure is the same for all ideal gases
b. The average translational kinetic energy per molecule of oxygen gas is 3 kT, k being Boltzmann constant
c. The mean-free path of molecules increases with decrease in the pressure
d. In a gaseous mixture, the average translational kinetic energy of the molecules of each component is different
Answer : A, C

Question. At what temperature, the sample of neon gas would be heated to double of its pressure, if the initial volume of gas is/are reduced to 15% at 75^oC ?
a. 319^oC
b. 592^oC
c. 128^oC
d. 60^oC
Answer : A

Question. If the v_rms is 30R^1/2 at 27^oC then calculate the molar mass of gas in kilogram:
a. 1
b. 2
c. 4
d. 0.001
Answer : D

Question. Let v, v_rms and v_p respectively denote the mean speed, root mean square speed and most probable speed of the molecules ion an ideal monoatomic gas at absolute temperature T. The mass of a molecule in m. Then:
a. no molecule can have a speed greater than √2v_rms
b. no molecule can have speed less than v_p/√2
c. v_p < v < v_rms
d. the average kinetic energy of a molecule is (3/4)mv²_p
Answer : C, D

Question. C_V and C_p denote the molar specific heat capacities of a gas at constant volume and constant pressure, respectively.
Then:
a. C_p − C_V is larger for a diatomic ideal gas than for a mono-atomic ideal gas
b. C_p + C_V is larger for a diatomic ideal gas than for a mono-atomic ideal gas
c. C_p/C_V is larger for a diatomic ideal gas than for a mono-atomic ideal gas
d. C_p•C_V is larger for a diatomic ideal gas than for a mono-atomic ideal gas
Answer : B, D

Question. Which of the following statement (s) is/are true regarding the Kinetic theory of gases?
a. The pressure of the gas is directly proportional to the average speed of the molecules
b. The root mean-square speed of the molecules is directly proportional to the pressure
c. The rate of diffusion is directly proportional to the average speed of the molecules
d. The average Kinetic energy per molecule is directly proportional to the absolute temperature
Answer : C, D

Question. According to Kinetic Theory of Gas which one of the following statements (s) is/are true?
a. Real gas behaves as ideal gas at high temperatures and low pressures
b. Liquid state of ideal gas is impossible
c. At any temperature and pressure ideal gas obeys the Boyle’s law and Charle’s law
d. The molecules of real gas do not exert any force on one another
Answer : A, B, C

Question. A mixture of NO₂ and N₂O₄ has a vapour density of 38.3 at 300K.What is the number of moles of NO₂ in 100g of the mixture?
a. 0.043
b. 4.4
c. 3.4
d. 0.437
Answer : D

Question. The relative rates of diffusion of O₂ and CH₄ through a container containing O₂ and CH₄ in 3 : 2 mass ratio will be
(a) 3√2/4
(b) 3/4√2
(c) 3/2√2
(d) None of these
Answer: C

Question. When an open vessel is heated from 300 K to 500 K, where % of the gas will escape out?
(a) 20
(b) 60
(c) 40
(d) 80
Answer: C

Question. A mixture containing 1.12 litres of H₂ and 1.12 litres of O2 at NTP is taken inside a bulb connected to another bulb by a stopcock with a small opening. The 2nd bulb is fully evacuated. The stop cock is opened for some time and then closed. The 1st bulb is now found to contain 0.05 gm H₂. Then % weight of H2 and O₂ in the 2nd bulb are
(a) 41.6%, 58.3%
(b) 58.3%, 41.6%
(c) 40%, 60%
(d) 60%, 40%
Answer: A

Question. The compressibility factor for 1 mole of van der Waal’s gas at 0°C and 100 atm is found to be 0.5. Assuming that volume of a gas molecule is negligible, calculate the van der waal’s constant ‘a’?
(a) 0.125 lit² atm mol^–2
(b) 1.25 lit² atm mol^–2
(c) 2.5 lit² atm mol–2
(d) 3.5 lit² atm mol^–2
Answer: B

Question. A vessel of volume 5 litres contain 1.4 gm N₂ at a temperature of 1800 K. Find the pressure of the gas of 30% of N2 molecule are dissociated into Nitrogen atoms at this temperature?
(a) 1.42 atm
(b) 19.2 atm`
(c) 2.40 atm
(d) 4.2 atm
Answer: A

Question. According to Charle’s law, at constant pressure 100 ml of a given mass of a gas with 10^ºC rise in temperature will become (1/273 = 0.00366)
(a) 100.0366
(b) 99.9634
(c) 103.66
(d) 100.366
Answer: C

Question. If the collision frequency of a gas at one atm pressure is Z then its collision frequency at 0.5 atm is
(a) 1.0 Z
(b) 4 Z
(c) 2 Z
(d) 0.25 Z
Answer: D

Question. If the mean free path is l at one atm pressure then its value at 5 atm pressure is
(a) 5 l
(b) 50 l
(c) l/5
(d) l/50
Answer: C

Question. Consider an ideal gas contained in a vessel. If the intermolecular interactions suddenly begins to act, which of the following will happen :
(a) The pressure decreases
(b) The pressure increases
(c) The pressure remains unchanged
(d) The gas collapses
Answer: A

Question. Equal number of moles of hydrogen and oxygen gases are placed in a container and the resulting mixture has a pressure of 380 mm of Hg. If oxygen is removed from the container, the remaining hydrogen gas at the same temperature has pressure equal to
(a) 380 mm of Hg
(b) 190 mm of Hg
(c) 760 mm of Hg
(d) 1520 mm of Hg
Answer: A

Question. A spherical balloon of 18 cm diameter is to be filled up with gas at NTP from a gas cylinder containing the gas at 30 atm pressure at 27ºC. If the gas cylinder can hold 3 litres of water, the number of balloons that can be fully filled is
(a) 400
(b) 26
(c) 100
(d) 50
Answer: B

Question. A small bubble rises from the bottom of a lake, where the temperature and pressure are 4ºC and 3.0 atm, to the water’s surface, where the temperature is 25ºC and pressure is 0.95 atm. Calculate the final volume of the bubble, if its initial volume was 2.1 mL
(a) 0.72 mL
(b) 6.2 mL
(c) 7.1 mL
(d) 22.4 mL
Answer: C

Question. The kinetic energy of N molecules of O₂ is x joule at 123ºC. Another sample of O2 at 27^ºC has a kinetic energy of 2x joule. The latter sample contains
(a) N molecules of O₂
(b) 2N molecules of O₂
(c) N/2 molecules of O₂
(d) None of these
Answer: A

Question. The gas which can be easily liquified is
(a) H₂
(b) CO₂
(c) He
(d) N₂
Answer: B

Question. Which gas can be easily adsorbed over charcoal
(a) H₂
(b) N₂
(c) He
(d) CH₄
Answer: D

Question. The R.M.S. velocity of an ideal gas at 27ºC is 0.3 m/sec, R.M.S. velocity, at 927ºC is
(a) 3.0
(b) 2.4
(c) 0.9
(d) 0.6
Answer: D

Question. At S.T.P. the density of nitrogen monoxide is
(a) 3.0 gm/litre
(b) 30.0 gm/litre
(c) 1.34 gm/litre
(d) 2.68 gm/litre
Answer: C

Question. R.M.S. velocity of an ideal gas at constant pressure varies with density as
(a) d2
(b) d
(c) √d
(d) 1/√d
Answer: D

Question. A mixture of hydrogen and oxygen in the 2 : 1 volume ratio is allowed to diffuse through a porous partition. Calculate the composition of the gas coming out initially.
(a) 8 : 1
(b) 4 : 1
(c) 2 : 1
(d) 4 : 3
Answer: A

Question. If one litre of dry oxygen is bubbled through water and collected at the same temperature and pressure. The volume of it the would now be
(a) 1 L
(b) < 1 L
(c) > 1 L
(d) 2 L
Answer: B

Question. The average speed at T1K and the most probable speed at T2K of CO₂ gas is 9 × 104 cm s–1.
Calculate the value of T1 and T2.
(a) T1 = 1684 K, T2 = 2143 K
(b) T1 = 2465 K, T2 = 3154 K
(c) T1 = 3154 K, T2 = 2465 K
(d) T1 = 2143 K, T2 = 1684 K
Answer: A

Question. At constant volume, for a fixed number of moles of a gas, the pressure of the gas increases with rise of temperature due to
(a) Increase in average molecular speed
(b) Increased rate of collision between molecules and walls of container
(c) Increase in molecular attraction
(d) Decrease in mean free path.
Answer: B

Question. Rate of diffusion of a gas is
(a) Directly proportional to its density
(b) Directly proportional to its molecular weight
(c) Directly proportional to the square root of its molecular weight
(d) Inversely proportional to the square root of its molecular weight
Answer: D

Question. A real gas obeying vander Waal equation will resemble ideal gas if the
(a) Constants a and b are small
(b) a is large and b is small
(c) a is small and b is large
(d) Constants a and b are large
Answer: A

Question. According to kinetic theory of gases, for a diatomic molecule
(a) The pressure exerted by the gas is proportional to the mean velocity of the molecule
(b) The pressure exerted by the gas is proportionalto the root mean square velocity of the molecule
(c) The root mean square velocity of the molecule is inversely proportional to the temperature
(d) The mean translational kinetic energy of the molecule is proportional to the absolute temperature.
Answer: D

Assertion and Reason

Note: Read the Assertion (A) and Reason (R) carefully to mark the correct option out of the options given below:
a. If both assertion and reason are true and the reason is the correct explanation of the assertion.
b. If both assertion and reason are true but reason is not the correct explanation of the assertion.
c. If assertion is true but reason is false.
d. If the assertion and reason both are false.
e. If assertion is false but reason is true.

Question. Assertion: 1 mol of H₂ and O₂ each occupy 22.4 L of volume at 0°C and 1 bar pressure.
Reason: Molar volume for all gases at the same temperature and pressure has the same volume.
Answer : A

Question. Assertion: Pressure exerted by a mixture of reacting gases is equal to the sum of their partial pressures.
Reason: Reacting gases react to form a new gas having pressure equal to the sum of both.
Answer : D

Question. Assertion: A mixture of He and O₂ is used for respiration for deep sea divers.
Reason: He is soluble in blood.
Answer : C

Question. Assertion: Effusion rate of oxygen is smaller than nitrogen.
Reason: Molecular size of nitrogen is smaller than oxygen.
Answer : C

Question. Assertion: Greater the value of Vander Waal’s constant 'a' greater is the liquefaction of gas.
Reason: 'a' indirectly measures the magnitude of attractive forces between the molecules.
Answer : A

Question. Assertion: Carbon-dioxide has greater value of root mean square velocity μrms than carbon monoxide.
Reason: μrms is directly proportional to molar mass.
Answer : D

Question. Assertion: Wet air is heavier than dry air.
Reason: The density of dry air is more than density of water.
Answer : C

Question. Assertion: All molecules in a gas have some speed.
Reason: Gas contains molecules of different size and shape.
Answer : D

Question. Assertion: 1/4th of the gas is expelled if air present in an open vessel is heated from 27°C to 127°C.
Reason: Rate of diffusion of a gas is inversely proportional to the square root of its molecular mass.
Answer : B

Question. Assertion: Vander Waal’s equation is applicable only to non-ideal gases.
Reason: Ideal gases obey the equation PV = nRT.
Answer : B

Integer

Question. From the relation PV = RT calculate the value of the constant R for one gram mole of an ideal gas:
Answer : 2

Question. Two gases A and B, having the same temp. T, same pressure P and same volume V are mixed. If mixture occupies a volume V and has temp. T, the pressure of the mixture will be x P, where x =?
Answer : 2

Question. A surface is hit elastically and normally by n balls per second, each of mass m moving with velocity u. If each  ball is made to hit the same surface with velocity 2u, the force on the surface would become K times. What is the value of K?
Answer : 2

Question. Two identical cylinders contain helium at 3.5 atmosphere and argon at 2.5 atmosphere respectively. If both these gases are filled in one of the cylinder, what would be the pressure of the mixture?
Answer : 6

Question. The rms velocity of molecules of a gas at –73ºC and 1 atmospheric pressure 100 m/s. The temperature of the gas is increased to 527ºC and pressure is doubled. The rms velocity becomes K times. What is the value of K?
Answer : 2