Question

If the ionization energy for hydrogen atom is $13.6eV$, then the ionization energy for ${He}^{+}$ ion should be:

• A. $13.6eV$
• B. $6.8eV$
• C. $54.4eV$
• D. $72.2eV$

Answer 1

Answer: (C)

$54.4eV$

${I.E.}_{He}={I.E.}_H\times {\left(\frac{Z_{He}}{Z_H}\right)}^2$

${I.E.}_{He}=13.6eV\times {\left(\frac{2}{1}\right)}^2$

${I.E.}_{He}=13.6eV\times 4$

${I.E.}_{He}=54.4eV$
Option C is correct.