The ratio of the wavelengths for 2 → 1 transition in Li++, He and H is

Q: The ratio of the wavelengths for 2 → 1 transition in Li⁺⁺ , He and H is

(a) 1 : 2 : 3

(b) 1 : 4 : 9

(c) 4 : 9 : 36

(d) 3 : 2 : 1

Ans: (c)