The waves emitted when a metal target is bombarded with high energy electrons are

The structure of solids is investigated by using

Stopping potentials of $24, 100, 110$ and $115 \ kV$ are measured for photoelectrons emitted from a certain element (with $24 \ kV$ minimum) when it is irradiated with monochromatic $X-rays$. If this element is used as a target in an $X-ray$ tube,what will be the wavelength of the $K_{\alpha}$ line?

On increasing the number of electrons striking the anode of an $X-$ray tube,which one of the following parameters of the resulting $X-$rays would increase?

The minimum wavelength of $X$-rays emitted by an $X$-ray tube is $0.4125 \mathring{A}$. The accelerating voltage is ...... $kV$.

Assertion : Soft and hard $X-$ rays differ in frequency as well as velocity.
Reason : The penetrating power of hard $X-$ rays is more than the penetrating power of soft $X-$ rays.