What is the difference between uniform circular motion and nonuniform circular motion?

The angular acceleration.

Uniform circular motion means that the angular velocity is constant (there is not angular acceleration), while nonuniform circular means that the angular velocity changes.

You can deduct other consequences, like that the uniform circular motion implies that for a given distance from the center the linear speed is constant, while in a nonuniform circular motion, the linear speed at a given distance from the center of the movement will varies with the time.

Uniform circular motion is when the force is directed towards the center and nonuniform is when the force is not directed towards the center. all kinds of circular motions the direction of the velocity vector changes at every instant.
the uuniform circular motion is that in which magnitude of velocity (speed) is same at every instant.
in non uniform circular motion the speed keeps changing.

hope this help

The answer is b.the gaseous state is electrically positive, while the plasma state is electrically negative.