What is the energy (in J atom$^{-1}$) required for the following process? $\mathrm{Li}^{2+}(\mathrm{g}) \rightarrow \mathrm{Li}^{3+}(\mathrm{g})+\mathrm{e}^{-}$ (Take the ionization energy for the H atom in the ground state as $2.18 \times 10^{-18} \mathrm{~J}^{-1}$ atom$^{-1}$)

JEE Main · 2026 · 02 Apr 2026 · Shift 1 · Atomic Structure

What is the energy (in J atom

^{- 1}

) required for the following process?

Li^{2 +} (g) \to Li^{3 +} (g) + e^{-}

(Take the ionization energy for the H atom in the ground state as

2.18 \times 1 0^{- 18} J^{- 1}

atom

^{- 1}

)

Answer: (C)

For a one-electron, hydrogen-like species the ionisation energy scales as

Z^{2}

. The process removes the last electron of

L i^{2 +}

from the

n = 1

level with

Z = 3

, so

E = (2.18 \times 1 0^{- 18}) \times 3^{2} = 1.962 \times 1 0^{- 17} J ato m^{- 1}

JEE Main · 2026 · 02 Apr 2026 · Shift 1 · Single correct option