Question

What is the maximum number of emission lines when the excited electron of a H-atom in $n=6,$ drops to the ground state?

• A. 6
• B. 15
• C. 30
• D. 12

Answer 1

Answer: (B)

No. of lines $=\Sigma \left(n_2-n_1\right)=\Sigma (6-1)=\Sigma 5$

$=5+4+3+2+1=15$

Alternatively

$6\to 5,5\to 4,4\to 3,3\to 2,2\to 1,$

$6\to 4,5\to 3,4\to 2,3\to 1,$

$6\to 3,5\to 2,4\to 1,$

$6\to 2,5\to 1,$

$6\to 1$

(5 lines ) +(4 lines) + (3 lines ) + (2 lines) + (1 line ) = 15 lines