Strong reducing behaviour of $H_3PO_2$ is due to

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

$FeSO_4$ gives a brown ring with ........

The number of non-ionisable hydrogen atoms present in the final product obtained from the complete hydrolysis of $PCl_{5}$ is :

Give physical and chemical properties of dinitrogen.

On heating,lead$(II)$ nitrate gives a brown gas $(A).$ The gas $(A)$ on cooling changes to a colourless solid/liquid $(B).$ $(B)$ on heating with $NO$ changes to a blue solid $(C).$ The oxidation number of nitrogen in solid $(C)$ is :