Question

Given below are two statements labelled as Assertion (A) and Reason (R).
Assertion (A): Total number of octahedral voids present in the unit cell of cubic close packing including the one that is present at the body center, is four.
Reason (R): Besides the body center there is one octahedral void present at the center of each of the six faces of the unit cell and each of which is shared between two adjacent unit cells.

• A. Both A and R are true and R is the correct explanation of A
• B. Both A and R are true but R is not the correct explanation of A
• C. A is true but R is false
• D. A is false but R is true

Answer 1

The correct option is C A is true but R is false

Assertion is true but Reason is false.
Correct reason is that beside the body centre there is one octahedral void at centre of each of $12$ edges which is surrounded by six atoms. Out of six atoms four belongs to same unit cell ($2$ at corner and $2$ at face centre) and $2$ atoms belongs to adjacent unit cell.