Final answer:
Temperature and volume were the two properties of the gas that were changing, leading to an increase in pressure.
Step-by-step explanation:
The properties of the gas that were changing, leading to an increase in pressure, were temperature and volume. When the gas reached the equator, the temperature increased, causing the gas molecules to move faster and collide more frequently with the walls of the container. This increased the pressure. Additionally, as the gas expanded due to an increase in volume, the same number of gas molecules occupied a larger space, resulting in an increase in pressure.