Structure of Atom Part 1

According to Bohr's atomic theory,
I. kinetic energy of electron is ∝‌

Z2

n2

II. the product of velocity (v) of electron and principal quantum number (n),′vn′∝Z2.
III. frequency of revolution of electron in an orbit is ∝‌

Z3

n3

IV. coulombic force of attraction on the electron is ∝‌

Z3

n4

Choose the most appropriate answer from the options given below.