Correct Answer: Option 2 and 3 i.e. (2) fluoride ion, which is larger in radius than a fluorine atom (3) fluorine atom, which is smaller in radius than a fluoride ion
Reason:
Atomic radius of an atom/ion depends upon effective nuclear charge. Atomic radius and effective nuclear charge has inverse relation. When an electron added in a atom, as in the case of F + e- → F-, the effective nuclear charge decreases. This is because, in F atom there are 9 protons and 9 electrons, while in F- ion there are 9 protons and 10 electrons. Since, effective nuclear charge has decreased, the atomic size of F- is more as compared to F atom.