A metal sphere has a charge of + 10C. What is the net charge after 8.0 x 10^13 electrons have been placed on it?

Answer: 9.9999872 C

Explanation: In to answer this question we have to use the charge of the electron, that is eqaul to - 1.6*10^-19 C.

After that, we have to calculate the charge given by 8.0*10^13 electrons, then we an additional charge of: 8.0*10^13 * - 1,6*10^-19 C=1.28*10^-5C

Finally the net charge of the metal sphere, initially charged by + 10C is:

10C-1.28*10^-5C=9.9999872 C