Find A, B and C in the following reactions :

$$N{H_3} + A + C{O_2} \to {(N{H_4})_2}C{O_3}$$

$${(N{H_4})_2}C{O_3} + {H_2}O + B \to N{H_4}HC{O_3}$$

$$N{H_4}HC{O_3} + NaCl \to N{H_4}Cl + C$$

On treating a compound with warm dil. H₂SO₄, gas X is evolved which turns K₂Cr₂O₇ paper acidified with dil. H₂SO₄ to a green compound Y. X and Y respectively are :

Given below are two statements :

Statement I : $$\alpha$$ and $$\beta$$ forms of sulphur can change reversibly between themselves with slow heating or slow cooling.

Statement II : At room temperature the stable crystalline form of sulphur is monoclinic sulphur.

In the light of the above statements, choose the correct answer from the options given below :

The correct statement about B₂H₆ is :