First three nearest neighbour distance for primitive cubic unit cell will be (edge length of unit cell = a) 

Options

A. `a, sqrt2a, sqrt3a`
B. `sqrt2a, sqrt2a, a`
C. `a,sqrt2a,2a`
D. `a,sqrt2a,sqrt2a`

Answer

A

Explanation

For primitive cubic (simple cube) nearest neighbour distance along edge length .a. `2r=2((a)/(2))=.a.`
Next nearest neighbour distance along face diagonal `-sqrt2a`
Next nearest neighbour distance along body diagonal `=sqrt3a`