Class 12 > Unit # 15:Molecular Theory of Gases > Textbook M.C.Qs

Section B: Multiple Choice Questions (MCQs)

1. The relationship between temperature and average kinetic energy of particles in a gas is:

(a) temperature is inversely proportional to average K.E. (b) temperature is directly proportional to average K.E. (c) temperature is independent of average K.E. (d) temperature is proportional to the square of average K.E.

2. Standard conditions of temperature and pressure (STP) refer to a gas at:

(a) 0°C and 1 atm (b) 20°C and 1 atm (c) 25°C and 1 atm (d) 30°C and 101.3 kPa (1 atm)

3. If the temperature is kept constant and the volume of a gas is doubled, then pressure of a gas is:

(a) Reduced to ½ of the original value (b) Doubled (c) Reduced to ¼ of the original value (d) Quadrupled

4. The Avogadro's number is the number of molecules in:

(a) One mole of a substance (b) One kg of a substance (c) One m³ of a gas (d) One kilogram of hydrogen gas

5. Mean translational K.E. per molecule of an ideal gas at temperature T is:

(a) 3/2 KT (b) ½ KT (c) 2/3 KT (d) KT⁴

6. The normal human body temperature is:

(a) 98.6°F (37°C) (b) 99.6°F (37.4°C) (c) 100.4°F (38°C) (d) 101°F (38.3°C)

7. The pressure P, the density ρ and the mean square speed of molecules of an ideal gas are related by the equation:

(a) $P = \frac{1}{2}\rho\overline{v^2}$ (b) $P = \frac{1}{3}\rho\overline{v^2}$ (c) $P = \frac{2}{3}\rho\overline{v^2}$ (d) $P = \rho\overline{v^2}$

8. In air at S.T.P, the average speed of the:

(a) Oxygen molecules is greater than Nitrogen molecules (b) Nitrogen molecules is greater than Oxygen molecules (c) Oxygen molecules is approximately equal to Nitrogen molecules (d) Helium atoms is greater than both Oxygen and Nitrogen molecules

9. If the absolute temperature of a gas is increased 3 times, the rms velocity of the molecules will be:

(a) 3 times (b) 9 times (c) $\sqrt{3}$ times (d) 1/3 times

10. A gas is enclosed in an isolated container which is placed on a fast-moving train uniformly. The temperature of the gas:

(a) Increases due to the motion of the train (b) Decreases due to the motion of the train (c) Remains constant (d) Fluctuates, depending on the train's speed