Practicing Success

Target Exam

CUET

Subject

Physics

Chapter

Atoms

Question:

Case : Read the passage and answer the question(s).

Hydrogen spectrum consists of discrete bright lines in a dark background and it is specifically known as hydrogen emission spectrum. There is one more type of hydrogen spectrum that exists where we get dark lines on the bright background, it is known as absorption spectrum.

Balmer found an empirical formula by the observation of a small part of this spectrum and it is given by : \(\frac{1}{λ}\) = R(\(\frac{1}{2^2}\) - \(\frac{1}{n^2}\)) , where n = 3,4,5,...

For Lyman series, the emission is from first state to nth state, for Paschen series, it is from third state to nth state, for Brackett series, it is from fourth state to nth state and for Pfund series, it is from fifth state to nth state.

The ratio of the wavelength for 2→1 transition in Li++, He+ and H is given by which of the following ?

Options:

1:2:3

1:4:9

4:9:36

3:2:1

Correct Answer:

4:9:36

Explanation:

λ ∝ \(\frac{1}{Z^2}\)