Question

Read the given statements and decide which is/are correct on the basis of kinetic theory of gases

(I) Energy of one molecule at absolute temperature is zero

(II) rms speeds of different gases are same at same temperature

(III) For one gram of all ideal gas kinetic energy is same at same temperature

(IV) For one mole of all ideal gases mean kinetic energy is same at same temperature

• A. All are correct
• B. I and IV are correct
• C. IV is correct
• D. None of these

Answer 1

Answer: (C)

IV is correct

Answer 2

If the gas is not ideal then its molecule will possess potential energy. Hence statement (I) is wrong.

rms speed of different gases at same temperature depends on its molecular weight $\left( v_{rms} \propto \frac{1}{\sqrt{M}} \right)$. Hence statement (II) also wrong.

Kinetic energy of one gram gas depends on the molecular weight $\left( E_{gm} \propto \frac{1}{M} \right)$. Hence statement (III) also wrong.

But K.E. of one mole of ideal gas does not depends on the molecular weight $\left( E = \frac{3}{2}RT \right)$. Hence (IV) is correct.