Which term describes a model in which a charge takes up no space and acts uniformly on its surroundings?

The correct answer is Point charge.

Explanation:

A point charge is located at a single point in a space. It is zero dimensional. It can be positive or negative. The electric field is the surrounding of the charge in which the electric force can be experienced.

The direction of the electric field lines for a positive point charge is outward. The direction of the electric field lines for a negative point charge is inward. These lines are uniform in nature.

Therefore, the point charge takes up no space. It acts uniformly on its surrounding.

d. air pressure decreases as altitude increases.