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The time period of revolution of electron in its ground state orbit in a hydrogen atom is 1.6 × 10⁻¹⁶ s. The frequency of revolution of the electron in its first excited state (in s⁻¹) is:

1. 1.6 × 10¹⁴
2. 7.8 × 10¹⁴
3. 6.2 × 10¹⁵
4. 5.6 × 10¹²

Correct answer: 7.8 × 10¹⁴

Solution

The frequency of revolution is inversely proportional to the time period of revolution. Since the time period for the ground state is given, we can use the relationship between energy levels and their corresponding frequencies to determine that the first excited state has a shorter time period, resulting in a higher frequency of 7.8 × 10¹⁴ s⁻¹.

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