If energy of electron in ground state is -13.6 eV, then find out speed of electron in fourth orbit of H-atom.

Correct option is B. 5.45×105m/s
As we know that
According to Bohr's Model ,Velocity of electron in nth orbit of atom with Atomic no. z
V = 2.18×106×z/n m/s
Here For H-atom z=1, n=4
V = 2.18×106×1/4 = 0.545×106m/s = 5.45×105m/s.