Question

suppose that the charge on the electron and proton did not have the same magnitude but instead differed by one part in 10^10. What would be the net charge on a 1.0 kg sample of helium gas?

Answer 1

1000 g of He is 250 moles
It would contain 250 Nav He atoms and 500 Nav protons and electrons.

(Nav is Avogadro's number)

Multiply 250 Nav by 10^-10 of the proton charge (e), and you get a net charge of
250*6.02*10^23*1.6*10^-29 C = 0.00241 C

Answer 2

the difference of charge between one electron and one proton will be equal to(1.6*10^-19)*(1/10^10), since there are two electrons and two protons in helium, multiply by 2 to get the charge of one atom of helium.

number of moles of He:
n(He)= m/M = 1000g/4g/mol = 250 mol

number of atoms of He:
N(He)= n*Na = 250*6.022*10^23.

so charge of 1kg of helium = 250*6.022*10^23*2*(1.6*10^-19)*(1/10^10) = 4.8*10^-3 C or 4.8 mc