(a) What equal positive charges (in Coulombs) would have to be placed on two celestial objects with masses 9.40 x 1027 and 1.99 x 1022 kg to neutralize their gravitational attraction? (b) What mass of hydrogen would be needed to provide the positive charge calculated in (a)?

Question

I was able to get the first part right. My answer was 1.18 x 10^15 C.
For b, using q = ne, do I just have to divide it by the constant e?
It won't accept my answer though.

Answer 1

If you have Q correct, then you should be able to use
Q = n e for the number of hydrogen atoms (protons) needed, n. You would have to divide that by Avogadro's number, or multiply it by the mass of a proton, to get the mass of all the protons.

hydrogen mass (g) = (number of hydrogen nuclei)(1 gm/mole)/(# of atoms/mole)

Answer 2

Do the following calculations, and write the answers with the correct number of significant figures.
(a) 15.45 m 8.21 m