When a soap bubble is charged?

Two metal plates are separated by $$2 \mathrm{~cm}$$. The potentials of the plates are $$-10 \mathrm{~V}$$ and $$+30 \mathrm{~V}$$. The electric field between the two plates is

Two protons are kept at a separation of $$10 \mathrm{~nm}$$. Let $$F_n$$ and $$F_e$$ be the nuclear force and the electrostatic force between them

A certain charge $$2 Q$$ is divided at first into two parts $$q_1$$ and $$q_2$$. Later the charges are placed at a certain distance. If the force of interaction between two chagrges is maximum then $$\frac{Q}{q_1}$$ is