The lifetime of an electron in the state in hydrogen is about 10 ns. We have to calculate the uncertainty in the energy of the state and compare it with the energy of this state.

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According to the Heisenberg’s uncertainty principle

,

where is the uncertainty in energy and is the uncertainty in time that is the lifetime of a state. It is given that the lifetime of an electron in the state in hydrogen is about 10 ns. Therefore, the uncertainty in the energy of the state will be

The energy of the state is

Ratio of the uncertainty in energy of the state and its energy will be