Question

Assertion :$FrCl$ has $CsCl$ structure with coordination number 8. Reason: $CN$ 8 is favoured by the large cation size.

Read the above assertion and reason and choose the correct option regarding it.

• A. Both Assertion and Reason are correct and Reason is the correct explanation for Assertion
• B. Both Assertion and Reason are correct but Reason is not the correct explanation for Assertion
• C. Assertion is correct but Reason is incorrect
• D. Assertion is incorrect but Reason is correct

Answer 1

The correct option is A Both Assertion and Reason are correct and Reason is the correct explanation for Assertion

Limiting radius ratio	Co-ordination number	Shape	Example
< 0.155 $\frac{r^{+}}{r^{-}}$	2	Linear	$Be{F}_2$
0.155 - 0.225	3	Trigonal planar	$B_2{O}_3$
0.225 - 0.414	4	Tetrahedeal	$ZnS,Si{O}_4^{4-}$
0.414-0.732	4	Square planar	$PtC{l}_4^{2-}$
0.414 - 0.732	6	Octahedreal	$MgO$
0.732 - 0.999	8	Body centred cubic	$CsCl$

From table it can be seen that as limiting radius ration increases, coordination no. increases.