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 \rightarrow 5 ,\,\,\,\, 5 \rightarrow 4 ,\,\,\, 4 \rightarrow 3,\,\,\,\, 3 \rightarrow 2,\,\,\,\, 2 \rightarrow 1,\,\,\,\, $

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

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

$6 \rightarrow 2,\,\,\,\, 5 \rightarrow 1,\,\,\,\, $

$6 \rightarrow 1$

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