The first `(Delta_(i)H_(1))` and second `(Delta_(i)H_(2))` ionization enthalpies `("in kJ mol"^(-1))` and the electron gain enthalpy `(Delta_(eg)H)("in kJ mol"^(-1))` of the elements I, II, III, IV and V are given below

the least reactive non - metal and the most reactive metal of these are respectively

Options

A. I and V
B. V and II
C. II and V
D. IV and V

Answer

C

Explanation

Element II : `Delta_iH_1` is lowest and there is sudden jump between the values of `Delta_iH_1 and Delta_i H_2` so its oxidation state is +1 and this element (metal) will be the most reactive metal.
Element V : The value of electron gain enthalpy `(Delta_(eg) H)` is positive. It means that energy is required to gain one electron.
Thus this non-metal will be the least reactive one.