Answer:
[tex]4.38\cdot 10^{13}[/tex] electrons
Explanation:
The net charge on the sphere is equal to:
[tex]Q=-7\cdot 10^{-6}C[/tex]
This charge is made up of N electrons. Each electron carries a charge of
[tex]q=-1.6\cdot 10^{-19}C[/tex]
So the total charge is just the number of electrons times the charge of each electron:
[tex]Q=Nq[/tex]
And solving the equation for N, we find the number of electrons:
[tex]N=\frac{Q}{q}=\frac{-7\cdot 10^{-6}C}{-1.6\cdot 10^{-19} C}=4.38\cdot 10^{13}[/tex]
