Question

The ionisation energy of $10$ times ionised sodium atom is

• A. $\frac{13.6}{11}\,eV$
• B. $\frac{13.6}{112}\,eV$
• C. $13.6 \times (11)^{2}\,eV$
• D. $13.6\,eV$

Answer 1

Answer: (C)

The Bohr model of hydrogen atom can be extended to hydrogen like atoms. Energy of such
atom is given by $E_{n}=-\frac{13.6}{n^{2}}Z^{2}\,eV$
Ionisation energy $=|E_{n}|$
Here, $Z=11$ for Na atom, $10$ electrons are removed already, so it is $10$ times ionised. For the last electron to be removed, $n=1$
$\therefore $ Ionization energy $=\frac{13.6\times (11)^{2}}{1^{2}}eV$
$=13.6\times (11)^{2}\,eV$