Which form of phosphorus is thermodynamically most stable?

What is a $p$-block element? Discuss the gaseous elements and metallic properties of $p$-block elements.

The number of hydrogen atoms directly attached to the phosphorus atom in phosphorous acid is

In which oxidation state,group $15$ elements act as Lewis base?

Elements $X$ and $Y$ belong to Group $15$. The difference between the electronegativity values of $X$ and phosphorus is higher than that of the difference between phosphorus and $Y$. $X$ and $Y$ are respectively:

Give general information about the elements of the $p$-block.