A scientist was performing X-ray diffraction studies on a crystal having rock salt structure - Chemistry - The Solid State

Question

A scientist was performing X-ray
diffraction studies on a crystal having rock salt structure The
molecular mass of the crystal is 239g/mol The density of the
crystal was found to be 12 7 g/cm3 The scientist is
supposed to study only those crystals having edge length below 0 75
mm Show whether the crystal selected by the scientist was
appropriate or not

Ravjot Kaur · Accepted Answer

Dear studentWe know density, d=ZMa3NAa3 =ZMdNAhere a is the edge lengthZ is the coordination numberM is the molecular massNA is the Avagadro numberSo,a3 = 4×23912
7×6 023×1023     = 12
5×10-23 cm3a = 5×10-8 cm  =0
5nmSince the edge length is less than 0
75nm , the crystal selected by the Scientist was inappropriate
Regards