What condition causes a gas's kinetic energy to increase?

The kinetic energy of a gas is directly related to its temperature, which is a measure of the average kinetic energy of the gas particles. When the temperature of a gas increases, the energy of the individual gas molecules also increases, leading to more vigorous motion. This is due to the greater thermal energy imparted to the molecules, increasing their speed and causing more frequent and forceful collisions with the walls of the container, thereby enhancing the overall kinetic energy of the gas.

In contrast, decreasing temperature results in a decrease in kinetic energy, as the gas molecules slow down and move less vigorously. Changes in pressure or volume can also affect the behavior of a gas, but they do not directly impact the kinetic energy in the same way that temperature does. For instance, a decrease in pressure at constant temperature won't increase kinetic energy; it may lead to more expansion but maintain the same average kinetic energy. Similarly, increasing volume can allow gas molecules to spread out but does not inherently raise their kinetic energy unless the temperature also increases. Thus, increasing temperature is the clear factor that directly correlates with an increase in kinetic energy for a gas.