Which of the following is most acidic in nature?

Group number = 11 (Atomic number = 111)

Heavier element of p block do not from pπ− pπ bonds as their atomic orbital are so large and diffius that they cannot have effecitve overlapping.

The inertness of ? subshell electrons towards bond formation is known as inert pair effect. This effect increases down the group thus, for Sn,  oxidation state is more stable, whereas, for Pb,  oxidation state is more stable, i.e.,  is reducing while  is oxidising.

Reducing character increases from NH₃ to BiH₃.

Group 15 oxides of type E₂O₃ and E₂O₅ are not always basic.