Question

The largest wavelength in the ultraviolet region of the hydrogen spectrum is 122 rm. The smallest wavelength in the infrared region of the hydrogen spectrum (to the nearest integer) is

(a) 802 nm

(b) 823 nm

(c) 1882 nm

(d) 1648 nm

Answer 1

The correct option is (b) 823 nm.

Explanation:

The largest wavelength in the ultraviolet region of the hydrogen spectrum corresponds to the transition n = 2 to n = 1. That is,

The transition from n = ∞ ro n = 3 will produce the smallest wavelength in infrared region of the hydrogen spectrum. So,

Equations (i) and (ii) gives I = 823.5 nm