* Kinetic Molecular Theory: The behavior of gases is explained by the Kinetic Molecular Theory. One of the key principles is that the average kinetic energy of gas molecules is directly proportional to the absolute temperature.

* Temperature and Speed: Kinetic energy is related to the speed of the molecules. Therefore, if you increase the temperature of a gas, the average speed of the molecules increases.

* Rigid Container: In a rigid container, the volume is constant. This means the gas molecules have a fixed space to move around in.

* Increased Collisions: As the molecules move faster, they collide with the walls of the container more frequently and with greater force. This is why the pressure inside the container increases when you heat the gas.

In summary: In a rigid container, when the speed of gas molecules increases (due to an increase in temperature), the pressure inside the container also increases because of the increased frequency and force of collisions with the walls.