Question

How many spectral line will be observed when an electron jumps from $n=5$ to $n=1$ in the visible line spectra of $H$ spectrum?

• A. 10
• B. 3
• C. 6
• D. 8

Answer 1

The correct option is B 3

Given: Transition in $H-$spectra where $n_1=1$ and $n_2=5$.
We know, Total number of spectral line $=\frac{(n_2-n_1)(n_2-n_1+1)}{2}$
So, total number of lines $=\frac{(5-1)(5-1+1)}{2}$ = 10
The 10 transitions possible are $5\to 4$, $5\to 3$, $5\to 2$, $5\to 1$, $4\to 3$, $4\to 2$, $4\to 1$, $3\to 2$, $3\to 1$, $2\to 1$.
Now, transitions in visible regions are when electron jumps from $5\to 2$, $4\to 2$, $3\to 2$.
Three spectral lines will be obtained in the line spectrum.