Electric field \(\mathrm{E}=150\, \mathrm{N} / \mathrm{C}\)

Total surface charge carried by earth \(q=?\) According to Gauss's law.

\(\phi=\frac{q}{\epsilon_{0}}=E A\)

\( \text { or, }  q=\epsilon_{0} \mathrm{EA}\)

\(=\epsilon_{0} \mathrm{E} \pi r^{2} \)

\(=8.85 \times 10^{-12} \times 150 \times\left(6.37 \times 10^{6}\right)^{2} \)

\(=680 \mathrm{Kc} \)

As electric field directed inward hence 

\(\mathrm{q}=-680\, \mathrm{Kc}\)