Phosphonic acid $(H_3PO_3)$ is:

In which of the following reactions,$NO_2$ is not liberated?

Which of the following is $NOT$ a property of red phosphorus?

An orange solid $(X)$ on heating,gives a colourless gas $(Y)$ and a green residue $(Z).$ Gas $(Y)$ on treatment with $Mg,$ produces a white solid substance. Identify the white solid substance.

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

The reddish-brown coloured gas formed when nitric oxide is oxidised by air is