Answer
$2.8\times10^{-10}\,F$ or $280\,pF$
Work Step by Step
Given/known: $\kappa=5.6,$ $\varepsilon_{0}=8.854\times10^{-12}\,F/m,$ $A=0.35\,m^{2}$ and $d=0.062\,m$ (from part a).
Recall: $C=\frac{\kappa\varepsilon_{0}A}{d}$
Result: $C=\frac{5.6\times8.854\times10^{-12}F/m\times0.35\,m^{2}}{0.062\,m}=2.8\times10^{-10}\,F$
