Question

When the electron jumps from $5^{th}$ orbit to ground state, the number of spectral lines produced in the hydrogen spectrum is:

• A. $5$
• B. $10$
• C. $20$
• D. $1$

Answer 1

The correct option is B $10$

Number of spectral lines from $n_1$ to $n_2$:

= $\frac{(n_2-n_1+1)(n_2-n_1)}{2}$

$n_1=1$

$n_2=5$

Number of spectral lines $=\frac{5\times (5-1)}{2}$
$=10$