Question

In the diffraction of X-rays by the set of a plane, in some cases the resultant intensity is zero, these are caused by absent reflections, what is the number absent reflection is divided?

(a) 2

(b) 10

(c) 50

(d) 100

I got this question in exam.

My doubt stems from Definitions topic in chapter X-Ray Diffraction of Solid State Chemistry

Answer 1

The correct choice is (a) 2

Easiest explanation: These absent reflection is divided into two groups, first those that are absent due to some quirk in the structure and second those that are absent due to the symmetry or type of lattice possessed by the structure. The latter are known as systematic absences.