What is the solubility of phosphine $(PH_3)$ in water?

Which of the following pentahalides is $NOT$ formed?

Which of the following statements is not valid for oxoacids of phosphorus?

On heating lead $(II)$ nitrate gives a brown gas $'A'$. The gas $'A'$ on cooling changes to a colourless solid $'B'$. Solid $'B'$ on heating with $NO$ changes to a blue solid $'C'$. Identify $'A'$,$'B'$ and $'C'$,write the reactions involved,and draw the structures of $'B'$ and $'C'$.

‘Lapis-Lazuli’ is a blue-coloured precious stone. It is a mineral of the class:

State the melting point,boiling point,and specific gravity of $HNO_3$.