White phosphorus catches fire in air to produce dense white fumes. This is due to the formation of

$P_4 + 3NaOH + 3H_2O \to A + 3NaH_2PO_2$. Here,$A$ is:

The following are some statements related to $VA$ group hydrides:
$I$. Reducing property increases from $NH_3$ to $BiH_3$.
$II$. Tendency to donate lone pair decreases from $NH_3$ to $BiH_3$.
$III$. Thermal stability of hydrides decreases from $NH_3$ to $BiH_3$.
$IV$. Bond angle of hydrides decreases from $NH_3$ to $BiH_3$.
The correct statements are:

Bones glow in the dark because

Why does $NO_2$ dimerise?

Assertion : Molecular nitrogen is less reactive than molecular oxygen.
Reason : The bond length of $N_2$ is shorter than that of oxygen.