Which one of the following has a maximum tendency to form M3 ion ? A. N B. Bi C. P D. As

N
Bi
P
As

The correct answer is $\boxed{\text{B}}$. Bismuth (Bi) has the maximum tendency to form a $\ce{Bi^{3+}}$ ion. This is because bismuth has a relatively low electronegativity (2.02) and a large atomic radius (1.45 Å). This means that the bismuth atom has a relatively weak hold on its electrons, and it is relatively easy for it to lose three electrons to form a $\ce{Bi^{3+}}$ ion.

The other elements in the question, nitrogen (N), phosphorus (P), and arsenic (As), have higher electronegativities and smaller atomic radii than bismuth. This means that they have a stronger hold on their electrons, and it is more difficult for them to lose electrons to form $\ce{M^{3+}}$ ions.

In addition, nitrogen and phosphorus are both nonmetals, while bismuth is a metalloid. This means that nitrogen and phosphorus are more electronegative than bismuth, and they have a stronger hold on their electrons.

As a result, bismuth has the maximum tendency to form a $\ce{Bi^{3+}}$ ion.