# A metal crystallises into simple, body centred and face centred cubic structure, whose unit cell lengths areA1, A2 andA3 respectively. The correct order of lengths of the unit cells is:A) A1 < A2 < A3B) A2 < A3 < A1​ C) A1 < A3 < A2​ D) A3 < A1 < A2PLEASE EXPLAIN THIS ​

Dear student,

The correct option is (A).

Explanation:

The following formula will show, radius (r) is related to the unit cell length (a).
For BCC: a = sqrt(16/3)r       {sqrt = square root}
For FCC:  a = sqrt(8)r
For SC:     a = 2r

Therefore, FCC will have largest unit length and SC (simple cubic) have the lowest.
Order of unit length (a) is:
$FCC>BCC>SC$

Regards.

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