Hydrogen $(_1H^1 )$, Deuterium $(_1H^2 )$, singly ionised Helium $(_2He^4 )^+$ and doubly ionised lithium $(_3Li^6 )^{++}$ all have one electron around the nucleus. Consider an electron transition from n = 2 to n = 1. If the wave lengths of emitted radiation are $\lambda_1, \lambda_2, \lambda_3 \;and \;\lambda_4$ respectively then approximately which one of the following is correct?

Question

( A ) $\lambda_1 = \lambda_2 = 4\lambda_3 = 9 \lambda_4$
( B ) $\lambda_1 = 2\lambda_2 = 2 \lambda_3 = \lambda_4$
( C ) $\lambda_1 = 2\lambda_2 = 3\lambda_3 = 4\lambda_4$
( D ) $4\lambda_1 =2 \lambda_2 = 2\lambda_3 = \lambda_4$