Question

How many spectral lines are seen for hydrogen atom when electron jumps from n2=5 to n1=
1 in visible region a) 2 b) 3 c) 4 d) 5

Answer 1

Answer:

• Spectral lines in visible region will be 3

Explanation:

It is given that the spectral line jump from n₂ = 5 to n₁ = 1 in a Hydrogen atom. But as question states that we need to find the spectral lines in visible region (also called as Balmer series). and we know that for visible region (Balmer series) the value of n₁ is 2 and n₂ = 3,4,5..... . Now, from the spectral lines formula we know that,

⇒ No. of spectral lines = (n₂ - n₁) (n₂ - n₁ + 1)/2

Substituting and Solving,

⇒ No. of spectral lines = (5 - 2) (5 - 2 + 1) / 2

⇒ No. of spectral lines = (3) × (5 - 1) / 2

⇒ No. of spectral lines = 3 × (4) / 2

⇒ No. of spectral lines = 12 / 2

⇒ No. of spectral lines = 6

This is total no. of spectral lines but we need to find the actual no. spectral lines which falls on n₁ = 2.

So, the six spectral lines are,

• 5 → 4
• 5 → 3
• 5 → 2
• 4 → 3
• 4 → 2
• 3 → 2

Clearly we can see that 5 → 2 ,4 → 2 ,3 → 2 are landing on n₁ = 2 i.e. visible region.

∴ Spectral lines in visible region will be 3.