What does the $K\alpha$ characteristic $X$-ray represent?

When a metal target is bombarded with high-energy electrons,the electromagnetic waves generated are

$X$-rays of wavelength $0.1 \ \mathring A$ are allowed to fall on a metal and get scattered. The wavelength of the scattered radiation is $0.111 \ \mathring A$. If $h = 6.624 \times 10^{-34} \ J \cdot s$ and $m_0 = 9 \times 10^{-31} \ kg$,then the direction of the scattered photons will be:

For the production of $X$-rays of wavelength $0.1 \mathring{A}$,the minimum potential difference required will be.....$kV$.

When a beam of accelerated electrons hits a target,a continuous $X$-ray spectrum is emitted from the target. Which of the following wavelengths is absent in the $X$-ray spectrum,if the $X$-ray tube is operating at $40,000 \ V$?

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