Atoms question for NEET / JEE Main, with solution

Answer: (A) $54.4$ eV

Concept. Ground-state energy of a hydrogen-like ion: $E_1 = -13.6Z^2$ eV. The ionisation energy is $-E_1$.

Step 1. Substitute $Z = 2$. $E_1 = -13.6 \times 4 = -54.4$ eV, so $54.4$ eV removes the electron.

Answer. $54.4$ eV (Option A).

Solution by Sreeraj P, M.Sc Physics