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

Which of the following produces $NO_2$ gas on heating?

Given below are two statements:
Statement $I$: The $N-N$ single bond is weaker and longer than the $P-P$ single bond.
Statement $II$: Compounds of group $15$ elements in $+3$ oxidation state readily undergo disproportionation reactions.
In the light of the above statements,choose the correct answer from the options given below:

Which of the following statements is correct for $N_2O_4$?

In Haber's process,hydrogen is obtained by reacting methane with steam in the presence of $NiO$ as a catalyst. This process is known as steam reforming. Why is it necessary to remove $CO$ when ammonia is obtained by Haber's process?

The number of hydrogen atoms directly attached to the phosphorus atom in phosphorous acid is