which change increases the electric force between objects?\no two neutral objects are moved closer…

Explanation:

Step1: Recall electric - force formula

The electric force between two charged objects is given by Coulomb's law $F = k\frac{q_1q_2}{r^2}$, where $k$ is the Coulomb's constant, $q_1$ and $q_2$ are the charges of the two objects, and $r$ is the distance between them.

Step2: Analyze each option

1. Neutral objects have no net charge ($q_1 = q_2=0$), so $F = 0$. Moving them closer does not change the force ($F$ remains $0$).
2. Adding electrons to two negatively - charged objects increases their negative charges ($q_1$ and $q_2$ increase in magnitude). According to Coulomb's law, when $q_1$ and $q_2$ increase, the force $F$ increases.
3. For two oppositely - charged objects, moving them farther apart increases $r$. Since $F = k\frac{q_1q_2}{r^2}$, an increase in $r$ leads to a decrease in $F$.
4. Reducing the charge on two positively - charged objects decreases $q_1$ and $q_2$. According to $F = k\frac{q_1q_2}{r^2}$, a decrease in $q_1$ and $q_2$ leads to a decrease in $F$.

Answer:

Electrons are added to two negatively charged objects.