Question

Select the correct statements from the following.
(1) For tetragonal crystal, $a=b=c$ and $\alpha =\beta =\gamma =90^{\circ }$
(2) For $CsCl$ the radius ratio is between $0.732-1.0$
(3) In $Ca{F}_2$, the Coordination of $C{a}^{2+}$ and $F^{-}$ are 4 and 8 respectively.
(4) The maximum coordination number of an atom in a HCP crystal structure of an element is 12.

• A. Statement 1 and 2
• B. Statement 2 and 4
• C. Statement 3 and 4
• D. Statement 1 and 3

Answer 1

Answer: (B)

(1) For tetragonal crystal $a=b\ne c;\alpha =\beta =\gamma =90^{\circ }$

(2) For $CsCl$ , the Coordination No. is $8$ and for this $C.N,$.

radius ratio is between $0.732-1.00$.

(3) In $Ca{F}_2$ , the Coordination number of $C{a}^{2+}=8$ and $F-=4$ respectively.

(4) The maximum $C.N$ is $12$ for $HCP$ crystal structure.