Identify the element for which $+1$ oxidation state is more stable than $+3$ oxidation state.

The strong reducing property of hypophosphorus acid $(H_3PO_2)$ is due to

In the nitrogen family,the $H-M-H$ bond angle in the hydrides $MH_3$ gradually becomes closer to $90^o$ on going from $N$ to $Sb$. This shows that gradually

$Mg_3N_2(s) + H_2O \xrightarrow{R.T.} P \downarrow + Q \uparrow$. Excess $Q$ gas does not form a coloured complex with:

Which of the following oxides of nitrogen is the anhydride of $HNO_3$?

Which gas is used to provide an inert atmosphere?