Question
The ionic radii $$\left( {{\text{in}}\,\mathop {\text{A}}\limits^0 } \right){\text{of }}{N^{3 - }},{O^{2 - }}{\text{and}}\,{F^ - }$$ are respectively:
A.
$$1.71,1.40\,{\text{and}}\,1.36$$
B.
$$1.71,1.36\,{\text{and}}1.40$$
C.
$$1.36,1.40\,{\text{and}}\,1.71$$
D.
$$1.36,1.71\,{\text{and}}\,1.40$$
Answer :
$$1.71,1.40\,{\text{and}}\,1.36$$
Solution :
For isoelectronic species, size of anion increases as negative charge increases. Thus the correct order is
$$\eqalign{
& \,\,\,\,{N^{3 - }} > {O^{2 - }} > {F^ - } \cr
& \left( {1.71} \right)\,\left( {1.40} \right)\,\,\,\left( {1.36} \right) \cr} $$