In the following questions a statement of Assertion (A) followed by a statement of Reason (R) is given. Choose the correct answer out of the following choices.
(a) Assertion and Reason both are correct statements and Reason is correct explanation for Assertion.
(b) Assertion and Reason both are correct satements but Reason is not correct explanation for Assertion.
(c) Assertion is correct statement but Reason is wrong statement
(d) Assertion is wrong statement but Reason is correct statement.
Assertion (A) Total number of octahedral voids present in unit cell of cubic close packing including the one that is present at the body centre, is four.
Reason (R) Besides the body centre there is one octahedral void present at the centre of each of the six faces of the unit cell and each of which is shared between two adjacent unit cells.
(c) The assertion is a correct statement but Reason is an incorrect statement.
The assertion is true as in ccp atom present at face centre and corner of each unit cell which creates an octahedral void at each body centre and all twelve edges fo a unit cell as shown below
(c) All edge centres and body centre represent octahedral void. Total number of octahedral voids = 12 x 1/4 +1 = 4.
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 the same unit cell (2 at corner and 2 at face centre) and 2 atoms belong to the adjacent unit cell.