Under ordinary conditions of temperature and pressure, the particles in a gas are

In normal conditions gas particles remain very distant from each other. They rarely collide and are stable. When temperature increases the gas particles begin to move faster and collide more, reducing the distance. When pressure increases the gas particles also pick up kinetic speed and are also closer to each other.

The answer is falsegravitational force is independent of medium and depends only on the masses of the two objects and the distance between them.