Which one of the following contains a $P-O-P$ bond?

Which of the following is the most explosive?

Which of the following oxyacids does not contain a $P-O-P$ bond?

Mercury $(II)$ chloride solution on reaction with gaseous ammonia forms:

How many of the following reactions will form $PH_3$ gas?
$(1)$ $Ca_3P_2 + H_2O \to$
$(2)$ $H_3PO_3 \xrightarrow{\Delta} $
$(3)$ $P_4 + NaOH \to$
$(4)$ $H_3PO_4 \xrightarrow{\Delta} $
$(5)$ $HNO_3 + P_4O_{10} \to$
$(6)$ $P_4 + HNO_3 \to$

Which of the following oxides of nitrogen is the anhydride of nitrous acid?