The structural formula of hypophosphorus acid is

White phosphorus,when heated with conc. $NaOH$ solution in an inert atmosphere of $CO_2$,forms phosphine and a sodium salt of oxoacid of phosphorus,$'X'$. The oxidation state of phosphorus in $'X'$ is

What is the chemical formula of sodium pyrophosphate?

Which of the following pentahalides is $NOT$ formed?

In case of nitrogen,$NCl_3$ is possible but not $NCl_5$,while in case of phosphorus,$PCl_3$ as well as $PCl_5$ are possible. This is due to:

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: