The total energy of an electron in the first excited state of the hydrogen atom is about – 3.4 eV. What is
(a) the kinetic energy,

Explanation

To find the kinetic energy of an electron in the first excited state of a hydrogen atom, we can follow these steps:

### Step 1: Understand the Total Energy Formula
The total energy (E) of an electron in a hydrogen atom is given by the formula:
\[ E = -\frac{13.6 \, \text{eV}}{n^2} \]
where \( n \) is the principal quantum number.
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