Question

In a sample of hydrogen-like atom all of which are in ground state, a photon beam containing photos of various energies is passed. In absorption spectrum, five dark lines, are observed. The number of bright lines in the emission spectrum will be (assume that all transitions takes place).
A. `5`
B. `10`
C. `15`
D. None of these

Answer 1

Correct Answer - C
Number of lines in absorption spectrum `=(n - 1)`
`rArrr 5 = n-1 rArr n = 6`
`:.` Number of bright lines in the emission spectrum
`= (n(n - 1))/(2) = (6(6-1))/(2) = 15`