Atoms - Result Question 16

17. Hydrogen atom in ground state is excited by a monochromatic radiation of $\lambda=975 \AA$. Number of spectral lines in the resulting spectrum emitted will be

[2014]

(a) 3

(b) 2

(c) 6

(d) 10

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Answer:

Correct Answer: 17. (c)

Solution:

  1. (c) For the $\lambda=975 \AA$

$ \frac{1}{\lambda}=R(\frac{1}{n_1^{2}}-\frac{1}{n_2^{2}}) $

where $R$ is the Rydberg constant

Solving we get $n_2=n=4$

( $\because n_1=1$ ground state)

Therefore number of spectral lines

$=\frac{n(n-1)}{2}=\frac{4(4-1)}{2}=6$