Question

which change increases the electric force between objects?
two neutral objects are moved closer together.
electrons are added to two negatively charged objects.
two oppositely charged objects are moved farther apart.
the charge on two positively charged objects is reduced.

Explanation:

The electric force between charged objects is given by Coulomb's law $F = k\frac{q_1q_2}{r^2}$, where $k$ is a constant, $q_1$ and $q_2$ are the charges of the objects, and $r$ is the distance between them. Adding electrons to two negatively - charged objects increases their charges ($q_1$ and $q_2$). According to the formula, an increase in charges leads to an increase in the electric force. Neutral objects have no electric force between them. Moving oppositely - charged objects farther apart or reducing the charge on positively - charged objects decreases the electric force.

Answer:

Electrons are added to two negatively charged objects.