The structure of solids is investigated by using

If the series limit of the Balmer series for hydrogen is $3646 \ \mathring{A}$,calculate the atomic number $(Z)$ of the element which gives an $X$-ray wavelength of the $K_{\alpha}$ line as $1.0 \ \mathring{A}$.

$X$-rays cannot be deflected by means of an ordinary grating due to

$X$-rays of wavelength $0.140 \,nm$ are scattered from a block of carbon. What will be the wavelengths of $X$-rays scattered at $90^{\circ}$ (in $\,nm$)?

$X$-rays of which of the following wavelengths are hardest? (in $\mathring{A}$)

The $K_{\alpha}$ characteristic $X$-ray refers to the transition: