The energy of a hydrogen atom in the ground state is –

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The energy of a hydrogen atom in the ground state is – 13.6 eV. The energy of a He+ ion in the first excited state will be

1. –13.6 eV
2. – 27.2 eV
3. – 54.4 eV
4. – 6.8 eV

Correct Option: A

Energy of a H-like atom in it's nth state is given by

E_n = -Z² ×	13.6	eV
	n²

For, first excited state of He⁺, n = 2, Z = 2

E_He⁺ = -	4	× 13.6 = - 13.6 eV
	2²