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Radiation coming from transitions n=2 to n=1 of hydrogen atoms fall on He⁺ ions in n=1 and n=2 states. The possible transition of helium ions as they absorb energy from the radiation is

Asked in JEE Main 8th April 1st Shift 2019 · Spectral series and wavelengths

• (1) n=2→ n=3
• (2) n=2→ n=5
• (3) n=1→ n=4
• (4) n=2→ n=4

Step-by-step solution

Why the other options are wrong

• (1) He⁺ 2→3 needs 7.56 eV, not 10.2.
• (2) 2→5 needs 11.4 eV.
• (3) 1→4 needs 51 eV.

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