Four identical metallic objects carry the following charges: +4.2 µC, +5.4 µC, -2.2 µC, and -4.4 µC. The objects are brought simultaneously into contact, so that each touches the others. Then they are separated.

Question

Four identical metallic objects carry the following charges: +4.2 µC, +5.4 µC, -2.2 µC, and -4.4 µC. The objects are brought simultaneously into contact, so that each touches the others. Then they are separated. 
How many electrons (or protons) make up the final charge on each object?

drwls · Answer

The total charge is 9.6-6.6 = +3.0 uC Each object gets 1/4 of that after they are contacted and separated. Divide by the electron charge, e, for the number of excess protons on each object.