If you have X-rays of the same λ, and they hit two crystals with the same packing but different atomic radii, the one with the smaller atoms will create a diffraction pattern in which the spacing of the points of coincidence
A. is smaller (answer)
B. is greater
C. is identical
I thought it would be greater, since if you have smaller radii, you will have a smaller lattice constant. And if you have a larger lattice constant, you will have a smaller d (from Bragg's Law, d being distance between atomic planes), unless I am misinterpreting the question.