d
Charge on Capacitor, \(\mathrm{Q}_{i}=\mathrm{CV}\)

After inserting dielectric of dielectric constant = \(\mathrm{K}\)

\(\mathrm{Q}_{\mathrm{f}}=(\mathrm{k} \mathrm{C}) \mathrm{V}\)

Induced charges on dielectric

\( \mathrm{Q}_{\mathrm{ind}} =\mathrm{Q}_{\mathrm{f}}-\mathrm{Q}_{\mathrm{i}}=\mathrm{KCV}-\mathrm{CV} \)

\(=(\mathrm{K}-1) \mathrm{CV}=\left(\frac{5}{3}-1\right) \times 90 \,\mathrm{pF} \times 2\, \mathrm{V}=1.2\, \mathrm{nc} \)