Question

What is the magnitude of the charge, in coulombs, of a lithium nucleus containing three protons and four neutrons? (charge of a proton is 1.6 x 10-19 c)?

Answer 1

The neutrons are electrically neutral, so they have net charge of zero. Therefore we should count only the charge given by the protons.

The nucleus contains three protons; each proton has a charge of $q=+1.6 \cdot 10^{-19} C$, therefore the net charge of the lithium nucleus will be
$Q=3 \cdot (+1.6 \cdot 10^{-19}C)=4.8 \cdot 10^{-19}C$

Answer 2

Answer: 4.8x10^-19 C