Assertion (A): Internal energy of real gas is always negative at absolute zero temperature.
Reason (R): Potential energy of a bounded system is negative.
1. Both (A) & (R) are true and the (R) is the correct explanation of the (A)
2. Both (A) & (R) are true but the (R) is not the correct explanation of the (A)
3. (A) is true but (R) is false
4. Both (A) and (R) are false
View Answer
At absolute zero, kinetic energy is minimal (zero for ideal gas). For a real gas, attractive intermolecular forces mean potential energy is negative (relative to infinite separation). So, total internal energy is negative. Thus, (A) is true. (R) is also true, as attractive forces in a bounded system lead to negative potential energy. (R) explains (A).
Assertion (A): The average translational kinetic energy of the molecules in one mole of all ideal gases, at the same temperature is the same.
Reason (R): The average kinetic energy of one mole of any ideal gas at temperature T is given by \( \frac{3}{2}RT \).
1. Both (A) & (R) are true and the (R) is the correct explanation of the (A)
2. Both (A) & (R) are true but the (R) is not the correct explanation of the (A)
3. (A) is true but (R) is false
4. Both (A) and (R) are false
View Answer
The average translational kinetic energy per mole for any ideal gas is \( \frac{3}{2}RT \), dependent only on T.
So (A) is true. The formula in (R) represents this average translational kinetic energy per mole. So (R) is true and correctly explains (A).