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. $13.6eV$

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 $=\frac{13.6\times (11{)}^2}{1^2}eV$
$=13.6\times (11{)}^{2}eV$