Explain why, diffusion occurs more quickly in a gas than in a liquid.

Diffusion occurs faster in gas because the kinetic energy of particles in the gaseous state is much higher than in liquid which makes the particles move faster.

In liquids, there is lesser space to move and also, the kinetic energy of particles is lower than gas particles. Collisions between the particles takes place while moving, are more frequent between the molecules in liquids, resulting in a slower rate of diffusion.