Question

In a collection of H-atoms, all the electrons jump from n=5 to ground level finally (directly or indirectly), without emitting any line in the Balmer series. The number of possible different radiation is

• A. 2
• B. 4
• C. 6
• D. 8

Answer 1

The correct option is C

6

Explanation for correct answers:

Option (C) 6

Step 1 Possible lines

The electrons jump from $\mathrm{n}=5$ to ground level

So the total number of possible lines is,

$$\begin{gathered} \frac{n(n-1)}{2}=\frac{5(5-1)}{2} \\ =\frac{5\times 4}{2} \\ =\frac{20}{2} \\ =10 \end{gathered}$$

Step 2 Number of possible different radiation

Balmer series should be excluded,

Therefore, the possible Balmer lines are;

$$\begin{gathered} 5\to 2 \\ 4\to 2 \\ 3\to 2 \\ 1\to 2 \end{gathered}$$

These 4 transitions will be excluded.

Total possible lines excluding the Balmer line is $10-4=6$

Therefore, The number of possible different radiation is $6$.

Hence option (C) 6 is correct.