Please help me with these questions?

Question

1)State the coulomb Law.

2)The force two identical charges seperated by 1cm is equal  to 90N.what is the magnitude of the two charges?

Answer 1

1) F=kQ1Q2/R^2 where F is the force between two charged particles, k=Coulomb's constant and R is the distance between them.

2) So, 90=kQ^2. Using k=9*10^9, Q^2=90/9 * 10^-9=10^-8, so Q=10^-4 or 0.0001 coulombs.