For an $X$-ray tube operating at $40 \, kV$, which of the following wavelengths is $NOT$ possible?

For characteristic $X$-ray of some material,which of the following relations is correct?

An electron beam in an $X$-ray tube is accelerated through a potential difference of $50000 \ V$. These are then made to fall on a tungsten target. The shortest wavelength of the $X$-ray emitted by the tube is

An $X$-ray tube is operated at $1.24$ million volts. The shortest wavelength of the produced photon will be ..... $nm$.

$X$-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 $\,nm$)?

Let ${\lambda _\alpha }$,${\lambda _\beta }$ and ${\lambda '_\alpha }$ denote the wavelengths of the $X-$ rays of the ${K_\alpha }, {K_\beta }$ and ${L_\alpha }$ lines in the characteristic $X-$ rays for a metal.