The molar heat capacity at constant pressure for Nitrogen gas at STP is nearly 3.5 R. Now, when the temperature is increased, it gradually increases and approaches 4.5 R. The most appropriate reason for this behaviour is that at high temperatures

The molar heat capacity at constant pressure for Nitrogen gas at STP is nearly 3.5 R. Now, when the temperature is increased, it gradually increases and approaches 4.5 R. The most appropriate reason for this behaviour is that at high temperatures molecular vibration gradually become effective.