\((A)\) \(KE =13.6 \frac{ z ^{2}}{ n ^{2}} \frac{ eV }{\text { atom }} \Rightarrow KE \alpha \frac{ z ^{2}}{ n ^{2}}\)

\((B)\) speed of \(e ^{-} \alpha \frac{ z }{ n }\)

\(\therefore \quad v \times n \alpha z\)

\((C)\) Frequency of revolution of \(e ^{-}=\frac{ v }{2 \pi r }\)

\(\therefore\) frequency \(\alpha \frac{z^{2}}{n^{3}}\)

\((D)\) \(F =\frac{ kq _{1} q _{2}}{ r ^{2}}=\frac{ kze ^{2}}{ r ^{2}} \quad\left\{ r \alpha \frac{ n ^{2}}{ z }\right.\)

\(\Rightarrow F \alpha \frac{ Z }{\left(\frac{ n ^{2}}{ Z }\right)^{2}}\)

\(\Rightarrow F \alpha \frac{ z ^{3}}{ n ^{4}}\)