The number of non-ionisable protons present in the product B obtained from the following reactions is ___________.

$$ \mathrm{C}_{2} \mathrm{H}_{5} \mathrm{OH}+\mathrm{PCl}_{3} \rightarrow \mathrm{C}_{2} {\mathrm{H}_{5} \mathrm{Cl}+\mathrm{A}} $$

$$\mathrm{A}\,{+}\, \mathrm{PCl}_{3} \rightarrow \mathrm{B}$$

Consider the following reactions:

PCl₃ + H₂O $$\to$$ A + HCl

A + H₂O $$\to$$ B + HCl

The number of ionisable protons present in the product B is _______________.

Consider the sulphides HgS, PbS, CuS, Sb₂S₃, As₂S₃ and CdS. Number of these sulphides soluble in 50% HNO₃ is ___________.

The number of halogen/(s) forming halic (V) acid is ___________.