What is the correct order of basicity of halides?

In the periodic table,with an increase in atomic number,how does the metallic character of an element change?

Which of the following will liberate bromine from a potassium bromide solution?

Among the statements $(I-IV)$,the correct ones are:
$(I)$ $Be$ has smaller atomic radius compared to $Mg$.
$(II)$ $Be$ has higher ionization enthalpy than $Al$.
$(III)$ Charge/radius ratio of $Be$ is greater than that of $Al$.
$(IV)$ Both $Be$ and $Al$ form mainly covalent compounds.

Which of the following pairs of elements belongs to the group of representative elements in the periodic table?

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.