The first ( $Δ_{r} H_{1}$ ) and the second ( $Δ_{r} H_{2}$ ) ionization enthalpies (in kJ $m o l^{- 1}$ ) and the ( $Δ_{e g} H$ ) electron gain enthalpy (in kJ $m o l^{- 1}$ ) of a few elements are given below:
Elements $Δ_{r} H_{1}$ $Δ_{r} H_{2}$ $Δ_{e g} H$
l 520 7300 -60
II 419 3051 -48
III 1681 3374 -328
IV 1008 1846 -295
V 2372 5251 +48
VI 738 1451 -40
Choose the correct option(s):

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The most reactive metal is II.

III and IV are both non-metals, III being the most reactive non-metal.

VI is a metal, and it can form a stable binary halide of the formula MX (X=halogen).

V is the most unreactive element.

answer is A, B, D.

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Detailed Solution

I, II, and VI must be metals as they have low $Δ_{r} H_{1}$ .
III and IV must be non-metals as they have large negative $Δ_{e g} H$ .
V must be a noble gas as it has high IEs as well as +ve $Δ_{e g} H$ .
VI may be a 2nd group metal as $Δ_{r} H_{1}$ relatively small and $Δ_{r} H_{2}$ is just about double.