The first $\left({\Delta }_{\text{i}}{\text{H}}_{\text{1}}\right)$  and the second $\left({\Delta }_{\text{i}}{\text{H}}_{\text{2}}\right)$ ionization enthalpies (in kJ${\text{mol}}^{–\text{1}}$ ) and the $\left({\Delta }_{\text{eg}}\text{H}\right)$  electron gain enthalpy (in kJ ${\text{mol}}^{–\text{1}}$) of a few elements are given below:

Number of the element	${\Delta }_{\text{i}}{\text{H}}_{\text{1}}$	${\Delta }_{\text{i}}{\text{H}}_{\text{2}}$	${\Delta }_{\text{eg}}\text{H}$
1	520	7300	-60
2	419	3051	-48
3	1681	3374	-328
4	1008	1846	-295
5	2372	5251	+48
6	738	1451	-40

Give the number of the elements, as per the table given above, that form a stable halide with formula ${\text{MX}}_{\text{2}}$ ( X= halogen)?