Modern Physics Ques 36
- Consider the spectral line resulting from the transition $n=2 \rightarrow n=1$ in the atoms and ions given below. The shortest wavelength is produced by
(1983, 1M)
(a) hydrogen atom
(b) deuterium atom
(c) singly ionised helium
(d) doubly ionised lithium
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Answer:
Correct Answer: 36.(d)
Solution:
Formula:
Wavelength Corresponding To Spectral Lines:
- Shortest wavelength will correspond to maximum energy. As value of atomic number $(Z)$ increases, the magnitude of energy in different energy states gets increased. Value of $Z$ is maximum for doubly ionised lithium atom $(Z=3)$ among the given elements. Hence, wavelength corresponding to this will be least.