Question

The limiting radius ratio for tetrahedral shape is

• A. 0 to 0.155
• B. 0.225 to 0.414
• C. 0.155 to 0.225
• D. 0.414 to 0.732

Answer 1

Answer: (B)

Limiting radius ratio The ratio of the radius of cation $(r^{+})$ to that of anion $(r^{-})$ is known as limiting radius ratio. It plays an important role in the crystal structure of ionic substance.

Limiting radius ratio $\left(\frac{r^{+}}{r^{-}}\right)$	Shape	Coordination number	Example
1. $0.115-0.225$	Plane trigonal	3	Boron oxide
2.$0.225-0.414$	Tetrahedral	4	$ZnS$
3.$0.414-0.732$	Square planar	4	-
4.$0.414-0.732$	Octahedral	6	$AgCl,MgO,NaBr$
4.$0.732-1.00$	Cubic	8	$CsCl,CsBr$