Q2 / 160 · TS EAMCET 2021 (06 Aug Shift 2) · Chemistry
The energy (in eV) associated with the electron in the lst orbit of $\mathrm{Li}^{2+}$ is
- Correct answerA−122.4
- B-61.15
- C-30.5
- D-244.6
Solution
Energy of an electron in hydrogen like species in $n$th shell is given by
$$
E=-13.6 \frac{Z^2}{n^2} \mathrm{eV}
$$
where, $Z=$ atomic number
$n=$ number of shell
For electron in first orbit of $\mathrm{Li}^{2+}$
$$
E_1=-13.6 \times \frac{3^2}{1^2} \mathrm{eV}=-122.4 \mathrm{eV}
$$
Hence, the correct answer is option: 'A'.