Why can not x rays pass through?

bcz x rays have very very small wave length.....

Ans: X-rays are diffracted by crystal because wave length of X-rays and interplanar spacing in the crystals is of the same order, (angstrom, Ã…), so it satisfies Bragg condition for diffraction

2dsinθ= nλ

Where n is the integer and determined by the order given, λ is the wave length of the x-rays, d is the spacing between the planes in the atomic lattice, and θ is the angle between the incident ray and the scattering planes (diffracted angle).