When cathode rays strike a metal target with a high melting point and high atomic number,what is produced?

The ionization energies of Cobalt $(Co)$,Copper $(Cu)$,and Molybdenum $(Mo)$ are $7.8 \, keV$,$9.0 \, keV$,and $20.1 \, keV$ respectively. If any of these metals are used as a target in an $X$-ray tube operating at $15 \, kV$,then:

The primary difference between $X$-rays and $\gamma$-rays is that:

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.

If the minimum wavelength of an $X$-ray is $2 \mathring{A}$,then the potential difference between the anode and the cathode is ...... $kV$.

The emission of continuous $X$-rays is due to: