Among these element groups, which is least likely to form ions?: 7A 3A 1A 4A

The element group which is least likely to form ions is 4A group

explanation

Element of group 4A has 4 valence electrons. for example Carbon which has [He] 2S2 2P2 electron configuration has 4 valence electrons.

Since 4A elements has 4 valence electrons, it means that their valence shell is half filled which is relatively stable. For this reason 4A element readily form ions.