NEET Chemistry Gaseous State MCQs Set A

Question. At what temperature the RMS velocity of oxygen molecules is equal to that of SO₂ at 300 K ?
(a) +123^ºC
(b) –123^ºC
(c) 27^ºC
(d) 600 K

Answer: B

Question. At very low pressure, the van der Waal’s equation for one mole is written as
(a) PV – pb = RT
(b) PV + a = RT
(c) PV = RT
(d) (P + a /V2)(V) = RT

Answer: D

Question. Values of van der Waal’s constant ‘a’ for three gases A, B and C are 5.6, 3.6 and 2.4 respectively.
The increasing order of their ease of liquefaction will be
(a) A, B, C
(b) C, B, A
(c) B, A, C
(d) B, C, A

Answer: B

Question. When 2 g of a gas A is introduced into an evacuated flask kept at 25ºC, the pressure is found to be one atmosphere. If 3 g of another gas B is then added to the same flask, the total pressure becomes 1.5 atmosphere. Asssuming ideal gas behaviour, calculate the ratio of molecular wt. MA: MB.
(a) 3 : 1
(b) 1 : 4
(c) 1 : 3
(d) None of these

Answer: A

Question. Equal time is taken by 100 ml hydrogen and 25 ml of a gas to diffuse through a porous partition. The mol wt. of the gas is
(a) 16
(b) 64
(c) 32
(d) None of these

Answer: C

Question. V 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 condition is
(a) 10 Seconds : He
(b) 20 Seconds : O₂
(c) 25 Seconds : CO
(d) 25 Seconds : CO₂

Answer: B

Question. A straight glass tube has two inlets X and Y at the two ends. The length of the tube is 200 cm. HCl gas through intel X and NH3 gas through inlet Y are allowed to enter the tube at the same time. White fumes first appear at a point P in side the tube. The distance of P from X is
(a) 81.12
(b) 0.8112
(c) 8.112
(d) None of these

Answer: A

Question. The temperature at which 5 moles of SO₂ will occupy a volume of 10 litres at a pressure of 15 atm.
using van der Waal’s constants a = 6.71 litre2 atm mole–1, b = 0.0564 litre mol–1
(a) 395.3 K
(b) 39.53 K
(c) 3953 K
(d) None of these

Answer: D

Question. A real gas approaches ideality at
(a) high temperature and high pressure
(b) high temperature and low pressure
(c) low temperature and low pressure
(d) low temperature and high pressure

Answer: B

Question. A container contains certain gas of mass m gm at a high pressure at P atm and temperature T k. A little amount of the gas was allowed to escape across a hole for sometime and then closed. Final temperature is 2/3 rd and final pressure is P/2 of the original. Then, calculate the ratio of the mass escaped and mass remained in the container?
(a) 2 : 1
(b) 1 : 4
(c) 4 : 1
(d) 10 : 1

Answer: B

Question. In a classroom there are 13 equidistant rows of benches and students are sitting on them. A class teacher releases laughing gas (N2O) from the front while a student releases tear gas (Molecular weight = 176) from the back of the classroom simultaneously then which row of students will laugh  and weep simultaneously?
(a) 4th
(b) 9th
(c) 6th
(d) 10th

Answer: B

Question. The ratio of velocities of diffusion of the gases A and B is 1 : 4. If the ratio of their masses is in the ratio of 2 : 3 (mixture) then ratio of their mole fraction is
(a) 10 : 1
(b) 1 : 10
(c) 24 : 1
(d) 1 : 24

Answer: D

Question. A hydrocarbon is composed of 85.7% carbon and 14.3% hydrogen by weight. It’s density is 2.28 gm lit–1 at 300 K and at 1 atm pressure. Then formula of the hydrocarbon is:
(a) C₂H₆
(b) C₃H₈
(c) C₄H₈
(d) C₄H₁₀

Answer: C

Question. A mixture of 0.5 mole CO and 0.5 mole CO₂ are contained in a container and allowed to effuse out across a pin hole into another vessel connected through a tube of negligible volume, which is vacant.
A total of “z” moles has effused in time “t” sec. If M1 and M₂ are the mean molar masses of gas mixture effused out and the gas mixture. Still remained in the first container then which one is correct?
(a) M₁z + M₂(1 – z) = 36
(b) M₁z + M₂(1 – 4z) = 10
(c) M2z + M₂(1 – z) = 36
(d) M₁z + M₂z = 2

Answer: A

Question. The composition of equilibrium mixture Cl₂ 2Cl which is attained at 1200°C is determined by measuring the rate of effusion through a pin-hole. It is observed that at 1.8 atm Hg, mixture effuses 1.16 time as that of Kr(Atomic weight = 84) effusing under the same condition. The % fraction of Cl₂ dissociated into Cl atoms is
(a) 1.37%
(b) 13.7%
(c) 20%
(d) 35.2%

Answer: B

Question. Which is true regarding kinetic theory of gases?
(a) The molecular volume is negligible in comparison to the total volume of the gas
(b) The force of attraction between the molecules of the gas is negligible
(c) The average kinetic energy of the gas molecules is directly proportional to the absolute temperature of the gas
(d) All of the above

Answer: D

Question. 20% N₂O₄ molecules are dissociated in a sample of gas at 27ºC and 760 torr. The density of equilibrium mixture is
(a) 3.116 gL^–1
(b) 10.9 gL^–1
(c) 1 gL^–1
(d) 0.5 gL^–1

Answer: A

Question. According to Maxwell-Boltzmann law of gases, the average translational energy (K.E.) is
(a) kT/2 per molecule
(b) kT per molecule
(c) RT per molecule
(d) 3/2 kT per molecule

Answer: D

Question. 1 mole N₂, 3 mole H₂ are mixed in 8.21 litres container at 300 K to form NH₃. If equilibrium average molecular mass was found to be 34/3 gm their total pressure of mixture (equilibrium) is
(a) 8 atm
(b) 4 atm
(c) 6 atm
(d) 9 atm

Answer: A

Question. At room temperature ammonia gas at 1 atm pressure and hydrogen chloride at p atmospheric pressure are allowed to diffuse through identical pin holes from opposite ends of a glass tube of 1 metre length and of uniform cross-section. Ammonium chloride is first formed at a distance of 60 cm from the end through which HCl gas is sent in. What is the value of p?
(a) 2.198 atm
(b) 21.9 atm
(c) 5.63 atm
(d) 1 atm

Answer: A