What is the difference between soft and hard $X-$rays?

For the production of characteristic $K_{\beta}$ $X$-rays,the electron transition is:

According to Moseley's law,the frequency of a spectral line in the $X$-ray spectrum varies as:

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

$X$-rays and $\gamma$-rays of the same energies may be distinguished by

The figure represents the observed intensity of $X-$rays emitted by an $X-$ray tube as a function of wavelength. The sharp peaks $A$ and $B$ denote: