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In fcc unit cell, atoms are numbered as ...

In fcc unit cell, atoms are numbered as shown below.
The atoms not touching each other are (Atom numbered `3` is face centre of front face)

A

`3` and `4`

B

`1` and `3`

C

`1` and `2`

D

`2` and `4`

Text Solution

Verified by Experts

The correct Answer is:
C
In fcc structure, corner atoms do not touch each other (atom `1` and `2`), but every face centre aton touches corners. Moreover, every face center atom touches every other face centre atom in an fcc unit cell.
i. Atoms `3` and `4` are `4` are touching each other where centre-to-centre distance `= (a)/(sqrt(2))`
ii. Atoms `1` and `2` are not touching each other.
iii. Atoms `2` and `4` are touching each other where centre-to-centre distance `= (a)/(sqrt(2))`
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