The most electropositive element possesses the electronic configuration

Observe the following data ($ \Delta_i H_1, \Delta_i H_2 $ and $ \Delta_{eg} H $ represent the first,second ionisation enthalpies and electron gain enthalpy respectively).

Element	$ \Delta_i H_1 $ $( kJ \ mol^{-1} )$	$ \Delta_i H_2 $ $( kJ \ mol^{-1} )$	$ \Delta_{eg} H $ $( kJ \ mol^{-1} )$
$ I $	$ 520 $	$ 7300 $	$ -60 $
$ I.I $	$ 490 $	$ 3051 $	$ -48 $
$ III $	$ 1681 $	$ 3374 $	$ -328 $
$ IV $	$ 2372 $	$ 5251 $	$ +48 $

Using the data,identify the most reactive metal.

The element having the electronic configuration $1s^2, 2s^2 2p^6, 3s^2 3p^1$ is

$Mg^{2+}$ is . . . . . . than $Al^{3+}$.

In the periodic table,the metallic character of elements

How many elements in the periodic table are gases? Provide their positions in the periodic table.