# MCQ | Gaseous State

QUIZ TEST – I

Q:1. If the pressure of a given mass of gas is reduced to half and temperature is doubled simultaneous the volume will be

(A) Same as before

(B) Twice as before

(C) 1/4 the as before

(D) None

Ans: (D)

Q:2. The molecules of a gas A travel four times faster than the molecules of gas B at same temperature. The ratio of molecular weights (MA/MB) is

(A) 1/16

(B) 4

(C) 1/4

(D) 16

Ans: (A)

Q:3. The ratio of rms velocity to average velocity of gas molecules at a particular temperature is

(A) 1.086 : 1

(B) 1 : 1.086

(C) 2 : 1.086

(D) 1.086 : 2

Ans: (A)

Q: 4. X ml of H2 gas effuses through a hole in a container in 5 secs. The time taken for effusion of same volume of gas specified below under identical condition is

(A) 10 secs : He

(B) 20 secs : O2

(C) 25 secs : CO

(D) 55 secs : CO2

Ans: (B)

Q:5. The compressibility factor for an ideal gas is

(A) 1.5

(B) 1

(C) 2

(D) 3

Ans: (B)

Q:6. On increasing temperature, the fraction of total gas molecule which has acquired most probable velocity will

(A) increase

(B) decrease

(C) remains constant

(D) cant say without knowing pressure

Ans: (B)

Q:7. Which of the following pair will diffuse at the same rate?

(A) CO2 and N2O

(B) CO2 and NO

(C) CO2 and CO

(D) N2O and NO

Ans: (A)

Q:8. The value of Vander Waals constant ‘ a ‘ is maximum for

(A) helium

(B) nitrogen

(C) CH4

(D) NH­3

Ans: (D)

Q:9. A mixture of H2 and O2 in 2:1 volume is allowed to diffuse through a porous partition what is the composition of gas coming out initially

(A) 1:2

(B) 4:1

(C) 8:1

(D) 1:4

Ans: (C)

Q:10. The temperature at which a real gas obeys the ideal gas laws at fairly wide range of pressure is

(A) Critical temperature

(B) Inversion temperature

(C) Boyle’s temperature

(D) Reduced temperature

Ans: (C)

Q:11.  I, II, III are three isotherm respectively at T1, T2 & T3 temperatures will be in order

(A) T1 = T2 = T3

(B) T1 < T­2 < T3

(C) T1 > T2 > T3

(D) T1 > T2 = T3

Ans: (B)

Q:12. NH3 is liquefied more easily than N2. Hence

(A) a and b of NH3 > that of N2

(B) a(NH3) > a(N2) but b (NH3) < b(N2)

(C) a(NH3) < a(N2) but b (NH3) > b(N2)

(D) None

Ans: (B)

Q:13. 0.2 mole sample of hydrocarbon CxHy yields after complete combustion with excess O2 gas, 0.8 mole of CO2, 1.1 mole of H2O. Hence hydrocarbon is

(A) C4H10

(B) C4H8

(C) C4H5

(D) C8H16

Ans: (A)

Q:14. When 2 gm A gas is introduced into an evacuated flask kept at 25°C, the pressure is found to be 1 atm. If 3g of another gas B is then added to same flask, the total pressure becomes 0.5 atm. The ratio of molecular weights is

(A) 1:1

(B) 1:2

(C) 2:3

(D) 1:4

Ans: (C)

Q:15. Air open vessel at 127°C is heated until 1/5th of air in it has been expelled. Assuming that the volume of vessel remains constant the temperature to which the vessel has been heated is

(A) 177°C

(B) 277°C

(C) 377°C

(D) 477°C

Ans: (D)

Q:16. 3.2 g S is heated if occupy a volume of 780 ml at 450°C and 723 mm pressure. Formula of sulphur is

(A) S2

(B) S

(C) S4

(D) S8

Ans: (D)

Q:17. A gas cylinder containing cooking gas can withstand a pressure of 14.9 atm. The pressure gauge of cylinder indicates 12 atm at 27°C. Due to sudden fire in building the temperature starts rising. The temperature at which the cylinder will explode is.

(A) 42.5°C

(B) 67.8°C

(C) 99.5°C

(D) 25.7°C

Ans: (C)

Q:18. A sample of gas is at 0oC. The temperature at which its rms speed of the molecule will be doubled is

(A) 103oC

(B) 273oC

(C) 723oC

(D) 818oC

Ans: (D)

Q:19. 6 g each of the following gases at 87oC and 750 mm pressure are taken. Which of them will have the least volume

(A) HF

(B) HCl

(C) HBr

(D) HI

Ans: (D)

Q:20. The temperature at which H2 has same rms speed (at 1 atm) as that of O2 at
NTP is

(A) 37 K

(B) 17 K

(C) 512 K

(D) 27 K