HARDMCQ SINGLEJEE Mains ChemistryPhysical ChemistryAtomic StructureIntro

The frequency of light emitted for the transition n = 4 to n = 2 of He⁺ is equal to the transition in H atom corresponding to which of the following?

0.n = 3 to n = 1
1.n = 2 to n = 1
2.n = 3 to n = 2
3.n = 4 to n = 3
Explanation

For He⁺ (Z=2): 1/λ = R_H × 4 × (1/4 − 1/16) = R_H × (1 − 1/4) = R_H(1/1 − 1/4). This equals H (Z=1): n=2→n=1 transition. So answer is n=2 to n=1 in H.

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