At higher temperatures, molal heat capacities for most of the gases (at constant pressure) __________ with increase in temperature.

ANS:B - increases

At higher temperatures, molal heat capacities for most gases (at constant pressure) increase with an increase in temperature. This increase in heat capacity occurs due to the additional degrees of freedom available to gas molecules at higher temperatures, allowing them to absorb more energy per degree of temperature rise. As the temperature of a gas increases, its molal heat capacity tends to increase as well. This phenomenon can be explained by considering the behavior of gas molecules at higher temperatures.

1. Increased Kinetic Energy: At higher temperatures, gas molecules possess higher kinetic energy. This increased kinetic energy allows the molecules to move with greater speed and exhibit more vigorous motion.
2. Additional Degrees of Freedom: With increased kinetic energy, gas molecules have access to additional degrees of freedom, such as vibrational and rotational motion, in addition to their translational motion. These additional degrees of freedom contribute to the internal energy of the gas.
3. Energy Absorption: As gas molecules absorb heat, they distribute this energy among their various degrees of freedom. At higher temperatures, the molecules can distribute this energy more effectively among their degrees of freedom, resulting in a greater capacity to absorb heat per degree of temperature rise.
4. Heat Capacity: Molal heat capacity measures the amount of heat required to raise the temperature of one mole of substance by one degree Celsius at constant pressure. As the gas molecules gain access to additional degrees of freedom and absorb more energy, the heat capacity of the gas increases.