The wavelength of an electromagnetic radiation is doubled, how will the energy of the photon change?

An electron in a hydrogen atom moves with a uniform speed in its stationary circular orbit of radius $5.3\times {10}^{-11} \mathrm{m}$. Find

(i) its speed and 

An electron in a hydrogen atom moves with a uniform speed in its stationary circular orbit of radius $5.3\times {10}^{-11} \mathrm{m}$. Find

(ii) energy in its ground state.