Question

In Bohr series of lines of hydrogen spectrum, the third line from the red end corresponds to which one of the following interorbit jumps of the electron for Bohr orbits in an atom of hydrogen?
(a) 3 → 2 

(b) 5 → 2

(c) 4 → 1 

(d) 2 → 5.

Answer 1

(b) : The electron has minimum energy in the first orbit and its energy increases as n increases. Here n represents number of orbit, i.e. 1^st, 2^nd, 3^rd.... The third line from the red end corresponds to yellow region i.e. 5. In order to obtain less energy electron tends to come in 1^st or 2^nd orbit. So jump may be involved either 5 → 1 or 5 → 2. Thus option (b) is correct here.