The average kinetic energy of the molecules in a gas sample would increase if the temperature increased from 20°C to 40°C. Here's why:

* Kinetic Energy and Temperature: The average kinetic energy of gas molecules is directly proportional to the absolute temperature (in Kelvin). This means that as temperature increases, the average kinetic energy of the molecules also increases.

* Kelvin Conversion:

* 20°C = 293.15 K

* 40°C = 313.15 K

* The temperature increase in Kelvin is significant.

In simpler terms: When you heat up a gas, you're giving its molecules more energy. This extra energy causes the molecules to move faster, leading to an increase in their average kinetic energy.