Which of the following forms of phosphorus is thermodynamically the most stable?

Which of the following statements is true regarding the properties of $PH_3$?

Which of the following statements is not true?

Which of the following oxides of nitrogen is a blue solid?

Identify the incorrect statements about group $15$ elements :
$A$. Dinitrogen is a diatomic gas which acts like an inert gas at room temperature.
$B$. The common oxidation states of these elements are $-3, +3$ and $+5$.
$C$. Nitrogen has unique ability to form $p\pi-p\pi$ multiple bonds.
$D$. The stability of $+5$ oxidation states increases down the group.
$E$. Nitrogen shows a maximum covalency of $6$.
Choose the correct answer from the options given below.

Which of the following statements is $NOT$ correct?