The first `(Delta_(i)H_(1))` and second `(Delta_(i)H_(2))` ionisation enthalpies `("in" kJ mol^(-1))` and the `(Delta_(eg)H^(ө))` electron gain enthalpy `("in" kJ mol^(-1))` of a few elements are given below:
`{:("Elements",(Delta_(i)H_(1)),(Delta_(i)H_(2)),Delta_(eg)H^(ө)),(I,520,7300,-60),(II,419,3051,-48),(III,1681,3374,-328),(IV,1008,1846,-295),(V,2372,5251,+48),(VI,738,1451,-40):}`
Which of the above elements is likely to be
a. the least reactive element.
b. the most reactive metal.
c. the most reactive non-metal.
d. the least reactive non-metal.
e. the metal which can form a stable binary halide of the formula MX2 (X=halogen).
f. the metal which can form a predominantly stable covalent halide of the formula MX(X=halogen).

Options

A. P
B. Q
C. S
D. U

Answer

B

Explanation

Metal having low `IE_1` and higher `IE_2` corresponds to alkali metal. Hence, Q is most reactive metal (easily forms cation)