Bohr radius of H-atom is 2.12 × 10⁻¹⁰ m. Calculate energy at this level.

Solution:

Bohr radius formula:

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Given:

rₙ = 2.12 × 10⁻¹⁰ m

a₀ = 0.53 × 10⁻¹⁰ m

n² = 2.12 / 0.53 = 4

n = 2

Energy of nth orbit:

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E₂ = −13.6 / 4 = −3.4 eV

Converting into joule:

E = −5.44 × 10⁻¹⁹ J

Correct Answer: −5.44 × 10⁻¹⁹ J

Option: (1)