A 12.5 eV electron beam is used to bombard gaseous hydrogen at room temperature. It will emit: (a) 2 lines in the Lyman series and 1 line in the Balmer series (b) 3 lines in the Lyman series (c) 1 line in the Lyman series and 2 lines in the Balmer series (d) 3 lines in the Balmer series

Answer: (a). n = 3n = 2n = 1LymanLymanBalmer 12.5 eV can excite hydrogen up to n = 3 (needs 12.09 eV), not n = 4 (needs 12.75 eV). Possible lines: 3→1 and 2→1 end on n=1 (Lyman); 3→2 ends on n=2 (Balmer). So the answer is (a) 2 lines in Lyman and 1 line in Balmer series.

A 12.5 eV electron beam is used to bombard gaseous hydrogen at room… | JEE Main 2013 (25 Apr, Shift 1)

Q65JEE Main 2013 · 25 APR · SHIFT 1Medium

Transitions, Photon Emission & Excitation

A 12.5 eV electron beam is used to bombard gaseous hydrogen at room temperature. It will emit:

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Answer: (a)

12.5 eV can excite hydrogen up to $n = 3$ (needs 12.09 eV), not $n = 4$ (needs 12.75 eV).
Possible lines: $3\to1$ and $2\to1$ end on $n=1$ (Lyman); $3\to2$ ends on $n=2$ (Balmer).
So the answer is (a) 2 lines in Lyman and 1 line in Balmer series.

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