Question

Henry Moseley studied characteristic X-ray spectra of elements. The graph which represents his observation correctly is
Given v = frequency of X-ray emitted
Z = atomic number

• A.

  

• B.

  

• C.

  

• D.

  

Hint:

Moseley’s law shows that the square root of the frequency of X-rays emitted is linearly proportional to the atomic number of the element. Always match the correct mathemat ical relationship to the graph

Answer 1

The Correct Option is A

Moseley’s Law Analysis: 

Moseley’s law describes the relationship between the square root of the frequency of X-rays emitted (\(\nu\)) and the atomic number (\(Z\)). According to Moseley’s observations:

\[ \sqrt{\nu} \propto (Z - \sigma) \]

where \(\sigma\) is a constant that accounts for the screening effect of inner electrons. The graph of \(\sqrt{\nu}\) versus \(Z\) is a straight line, as frequency is directly proportional to the square of the atomic number minus the screening constant.

Analysis of Options:

1. \(\sqrt{\nu}\) vs \(Z\): This correctly represents Moseley’s observation, as the relationship is linear.
2. \(\sqrt{Z}\) vs \(\nu\): This is incorrect, as the relationship does not involve the square root of the atomic number.
3. \(\nu\) vs \(Z\): This does not follow Moseley’s law, as the relationship is not linear.
4. \(\nu^2\) vs \(Z\): This is incorrect, as the relationship is based on the square root of frequency,not the square of frequency.

Conclusion: The correct answer is option (1).