Answer
The slope value agrees with the value given for $C$ in Module $40-6$.
Work Step by Step
The Moseley plot using the given data is in bellow.
The slope of the straight line as shown in the graph is given by
$\text{Slope}=\frac{\Delta f^{1/2}}{\Delta Z}$
or, $\text{Slope}=\frac{(1.39573-1.24676)\times 10^{9}}{29-26}\;Hz^{1/2}=4.96\times 10^{7}\;Hz^{1/2}$
Therefore, the slope value agrees with the value given for $C$ in Module $40-6$.
