Question
In FCC unit cell distance b/w centre of two spheres which are touching each other & distance b/w centre of two nearest non touching sphere is
1) (2a)1/2,, 2a
2)2r, (a+r)
3) a/(21/2), a
4) both (2) & (3)
a= edge length. r= radius of atom
Joshi sir comment
along diagonal of a face 4r = a√2 or r = a√2/4 so distance b/w centre of two touching spheres is 2r = a√2/2
similarly distance b/w two nearst non touching sphere = a (along edge)
so 3) will be the option