The wavelength of $X$-rays is of the order of .......

$X$-rays incident on a material:

$\Delta \lambda$ is the difference between the wavelength of the $K_\alpha$ line and the minimum wavelength of the continuous $X$-ray spectrum when the $X$-ray tube is operated at a voltage $V$. If the operating voltage is changed to $V / 3$,then the above difference is $\Delta \lambda^{\prime}$. Then:

The wavelength of the most energetic $X$-ray emitted when a metal target is bombarded by $100 \text{ keV}$ electrons is approximately.......$ \mathring{A} $

An $X$-ray has a wavelength of $0.010 \mathring{A}$. Its momentum is

Which one of the following statements is $WRONG$ in the context of $X$-rays generated from an $X$-ray tube?