JEE Main · 2023 · Shift-ImediumPERI-002

It is observed that characteristic X-ray spectra of elements show regularity. When frequency to the power 'n' i.e. vn…

Classification of Elements & Periodicity · Class 11 · JEE Main Previous Year Question

Question

It is observed that characteristic X-ray spectra of elements show regularity. When frequency to the power ' $n$ ' i.e. $v^n$ of X-rays emitted is plotted against atomic number Z, the following graph (a straight line) is obtained. The value of ' $n$ ' is:

Options

a
1
b
2
c
$\frac{1}{2}$
✓
d
3

Correct Answerc

$\frac{1}{2}$

Detailed Solution

🧠 Moseley's equation directly gives the power Moseley's Law: $\sqrt{\nu} = a(Z - b)$ , which can be written as $\nu^{1/2} = a(Z - b)$ .

🗺️ Match the exponent The question says $\nu^n$ vs $Z$ gives a straight line. Compare: in Moseley's equation the exponent on $\nu$ is $\frac{1}{2}$ . So $n = \frac{1}{2}$ .

$\boxed{\text{Answer: (c)}}$

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