The gas produced from thermal decomposition of $(NH_4)_2Cr_2O_7$ is

The number of bridged oxygen atoms present in compound $B$ formed from the following reactions is
$Pb(NO_3)_2 \xrightarrow{673 \ K} A + PbO + O_2$
$A \xrightarrow{\text{Dimerise}} B$

The number of $P-O-P$ bonds in cyclic metaphosphoric acid is ....

The reaction of aqueous $NaOH$ with white $P_4$ is given by: $P_4 + NaOH (aq) \rightarrow PH_3 + X$. The compound $X$ is:

Which among the following oxides of nitrogen is called nitrogen sesquioxide?

Orthophosphorus acid on disproportionation gives $PH_3$ and another oxoacid of phosphorus '$X$'. The basicity of $X$ is