Charge from excess electrons and electron repulsion distance

[Jimmy215]

Homework Statement

I have a few questions which I have tried myself and have gotten a few answers, but I am unsure if they are right or not. If someone can confirm if I have them right it will be greatly appreciated on my part.

Homework Equations

How many excess electrons are needed to create a net charge of 100 Uc?.

Answer : 6.25 x 10^20 electrons.

2) How far apart must two electrons be in order that they expierience a force of repulsion of 1.0x10^-12 N?.

Answer: 3x10^21 m.

The Attempt at a Solution

 

[rl.bhat]

Any charge Q = n*e where e is the charge on an electron. Now check your answer.
For part (2) wright down the relevant equation.