JEE Main · 2026 · 06 Apr 2026 · Shift 2 · Atomic Structure

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The Bohr radius of a hydrogen like species is 70.53 pm . The species and the stationary state(n) are respectively
(Given: Hydrogen atom Bohr radius is 52.9 pm )

(A) $Li^{2 +}, 3$
(B) $He^{+}, 3$
(C) $He^{+}, 2$
(D) $Li^{2 +}, 2$ ✓ Correct

Answer: (D)

Solution

For a hydrogen-like species the Bohr radius is

r = a_{0} \frac{n ^{2}}{Z}

with

a_{0} = 52.9

pm, so

\frac{n ^{2}}{Z} = \frac{70.53}{52.9} = \frac{4}{3}

. This is met by

n^{2} = 4

and

Z = 3

, that is

n = 2

for a nuclear charge of 3. The species is

L i^{2 +}

in its second stationary state.

JEE Main · 2026 · 06 Apr 2026 · Shift 2 · Single correct option

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