question_answer

The unit cell cube length for LiCI (just like NaCI structure) is \[5.14\,\,\overset{\text{o}}{\mathop{\text{A}}}\,\]. Assuming anion- anion contact, the ionic radius for chloride ion is:

A) \[1.815\,\,\overset{\text{o}}{\mathop{\text{A}}}\,\]

B) \[2.8\,\,\overset{\text{o}}{\mathop{\text{A}}}\,\]

C) \[3.8\,\,\overset{\text{o}}{\mathop{\text{A}}}\,\]

D) \[4.815\,\,\overset{\text{o}}{\mathop{\text{A}}}\,\]

Correct Answer: A

Solution :

\[2({{r}_{C{{l}^{\Theta }}}}+{{r}_{C{{l}^{\Theta }}}})\,\,=\,\,\sqrt{2}\,a\] \[{{r}_{C{{l}^{\Theta }}}}+{{r}_{C{{l}^{\Theta }}}}\,=\,\frac{a}{\sqrt{2}}\,\,\Rightarrow \,\,{{r}_{C{{l}^{\Theta }}}}\,=\,\,\frac{a}{2\sqrt{2}}\,\]