Radiation coming from transitions n = 2 to n = 1 of hydrogen atoms fall on H e + ions in n = 1 and n = 2 states. The possible transition of helium ions as they absorb energy from the radiation is:

Step-by-step solution

E = 13.6 1 1 1 - 1 2 2   e V     . . . ( 1 ) For Helium: E = 13.6 2 2 1 n 1 2 - 1 n 2 2   e V   . . . ( 2 ) From equation ( 1 ) and ( 2 ) 13.6   3 4 = 13.6   4   1 n 1 2 - 1 n 2 2 1 n 1 2 - 1 n 2 2 = 3 16 From option, n 1 = 2 and n 2 = 4 are satisfying the equation.