Which of the following has the largest ionic radius?
For isoelectronic species (N³⁻, O²⁻, F⁻, Na+, all with 10 electrons), radius increases with decreasing nuclear charge. N³⁻ (Z=7) has the largest radius.
Ref: NCERT Class 11 Chemistry > Chapter 3: Classification of Elements and Periodicity in Properties > Topic: Electronic Configuration and Types of Elements - s p d f Blocks