Structure of Atom

According to Bohr's atomic theory : (A) Kinetic energy of electron is $\propto {{{Z^2}} \over {{n^2}}}$. (B) The product of velocity (v) of electron and principal quantum number (n), $'vn' \propto {Z^2}$. (C) Frequency of revolution of electron in an orbit is $\propto {{{Z^3}} \over {{n^3}}}$. (D) Coulombic force of attraction on the electron is $\propto {{{Z^3}} \over {{n^4}}}$. Choose the most appropriate answer from the options given below :