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JEE Main 2025 · PhysicsMultiple choiceSingle correctEasyCalculation

JEE Main 2 April 2025, Shift 2, Physics Q40

Question 40 of 75 in this shift, Physics question 15 of 25, Section A.

Assuming the validity of Bohr's atomic model for hydrogen like ions the radius of

\mathrm{Li^{++}}

ion in its ground state is given by

\frac{1}{X}a_0

, where

X =

__________. (Where

a_0

is the first Bohr's radius.)

(1) $1$
(2) $2$
(3) $3$ Official answer
(4) $9$

Official answer

Option 3

NTA final key.

Chapter: Atoms
Topic: Bohr's Atomic Model
Idea tested: Bohr Orbit Radius

Same idea in other shifts

Asked 2× in all

6 Apr 2023, Shift 1 · Q53The radius of fifth orbit of the $\mathrm{Li^{++}}$ is ____________ $\times10^{-12}$ m. Take: radius of hydrogen atom = 0.51 ÅEasyNumerical value

Question text from the official JEE Main paper published by NTA; answer from the final answer key. Chapter, topic and idea tags, difficulty and skill are Lumi’s. Lumi analyses 42 of the 174 JEE Main shifts held from 2017 to 2026.