Question

The transition from the state $n = 4$ to $n = 3$ in a hydrogen like atom results in ultraviolet radiation. Infrared radiation will be obtained in the transition from

• A. $2 ? 1$
• B. $3 ? 2$
• C. $4 ? 2$
• D. $5 ? 4$

Answer 1

Answer: (D)

$5 ? 4$

Answer 2

IR corresponds to least value of $\left(\frac{1}{n^{2}_{1}}-\frac{1}{n^{2}_{2}}\right)$ i.e. from Paschen, Bracket and Pfund series. Thus the transition corresponds to $5 ? 3.$