Question

Assertion (A) : In sodium chloride crystal, $N{a}^{+}$ ions occupy octahedral voids while $C{l}^{-}$ ions occupy vertices of octahedron.
Reason (R) : The radius ratio of $N{a}^{+}$: $C{l}^{-}$ lies between $0.4$ and $0.7$.

• A. Both (A) and (R) are correct and (R) is the correct explanation of (A)
• B. Both (A) and (R) are correct but (R) is not the correct explanation of (A)
• C. (A) is correct but (R) is incorrect
• D. (A) is incorrect but (R) is correct
• E. Both (A) and (R) are incorrect

Answer 1

Answer: (D)

(A) is incorrect but (R) is correct

Limiting radius ratio = r/R	Coordination Number of cation	Structural Arrangement (Geometry of voids)	Example
0.155-0.225 0.225-0.414 0.414-0.732 0.414-0.732 0.732-1.000	3 4 4 6 8	Plane Trigonal Tetrahedral Square planar Octahedral Cubic	Boron Oxide $ZnS,Si{O}_2$ - $NaCI,Mg{O}_2$ $CsCI$