1. Moseley’s law

Henry Moseley found that for characteristic X-rays, the frequency $\nu$ is related to atomic number $Z$ by

$\sqrt{\nu} = a(Z-b)$

where $a$ and $b$ are constants for a given series.

Equivalently,

$\nu = k(Z-b)^2$

So:

• $\nu$ is not linear in $Z$.
• $\sqrt{\nu}$ is linear in $Z$.

2. What graph should represent Moseley’s observation?

Since the question states the axes involve frequency $\nu$ and atomic number $Z$, the correct observation is:

$\nu \propto (Z-b)^2$

Thus the graph of $\nu$ versus $Z$ must be an upward-opening parabola.

If the graph were $\sqrt{\nu}$ versus $Z$, it would be a straight line.

3. Selecting the option

Among the given options, the one corresponding to Moseley’s observation is Option B.

4. Comparison with stored answer

Stored correct answer: B

My derived answer: B

Hence, they agree.