Question

The rate of effusion is maximum in?

Answer 1

Don’t confuse effusion process with diffusion process as they both are different. Diffusion is movement of particles from a high concentration to low concentration whereas effusion is movement of gas particles through a hole. Gaseous particles can move in any random motion and diffusion is faster at high temperatures.

Complete step-by-step solution:
Not only do gaseous particles move with high kinetic energy, but their small size enables them to move through small openings as well; this process is known as effusion. For effusion to occur, the hole’s diameter must be smaller than the molecules’ mean free path (the average distance that a gas particle travels between successive collisions with other gas particles).
Effusion is explained by the continuous random motion of particles; over time, this random motion guarantees that some particles will eventually pass through the hole. Graham’s Law states that as a consequence of the average molecular kinetic energy of two different gas molecules being equal at the same temperature. The rate of effusion is determined by the number of molecules that diffuse through the hole in a unit of time, and therefore by the average molecular velocity of the gas molecules.
So effusion rate is maximum in gases like in noble gas neon has fastest effusion rate.

Note: We need to know that the rate of diffusion is faster in gases because Diffusion in gases is quick because the particles in a gas move quickly. It happens even faster in hot gases because the particles of gas move faster. In rate of effusion, the opening of the hole must be smaller than the mean free path because otherwise, the gas could move back and forth through the hole.