Assertion (A) : Graphite is an example of tetragonal crystal system.
Reason (R ) : For a tetragonal system, `a = b != c` and `alpha = beta = 90^(@), gamma = 120^(@)`.

Options

A. If both `(A)` and `(R)` are correct, and `(R)` is the correct explanation of `(A)`
B. If both `(A)` and `(R)` are correct, but `(R)` is not the correct explanation of `(A)`
C. If `(A)` is correct, but `(R)` is incorrect.
D. If both `(A)` and `(R)` are incorrect.

Answer

D

Explanation

Correct (A): Graphite is an example of hexagonal crystal system in which each `C-`atom is `sp^(2)` hybridized and is linked to three other `C-`atom in a hexagonal planar structure.
Correct (R): For tetragonal system, `a = b ne c` and `alpha = beta = gamma = 90^(@)`. For hexagonal systems,
`a = b ne c` and `alpha = beta = 90^(@), gamma = 120^(@)`.