Hydrogen atom does not emit $X$-rays because

The wavelength of the $K_{\alpha}$ $X$-ray produced by an $X$-ray tube is $0.76 \ \mathring{A}$. The atomic number of the anode material is ...

$STATEMENT-1$: If the accelerating potential in an $X$-ray tube is increased, the wavelengths of the characteristic $X$-rays do not change. because
$STATEMENT-2$: When an electron beam strikes the target in an $X$-ray tube, part of the kinetic energy is converted into $X$-ray energy.

If the lattice constant of a crystal is $3 \times 10^{-8} \, cm$ and the glancing angle for the first-order diffraction of $X$-rays is $30^{\circ}$,then the value of $\lambda$ will be ..... $\times 10^{-8} \, cm$.

In an $X$-ray spectrum,if the wavelengths of $K_\alpha$,$K_\beta$,and $K_\gamma$ lines are $\lambda_\alpha$,$\lambda_\beta$,and $\lambda_\gamma$ respectively,then:

$A$ potential difference of $20 \, kV$ is applied across an $X-ray$ tube. The minimum wavelength of $X-rays$ generated (in $\mathring{A}$) is