Identify the compound that exhibits tautomerism.

Ozonolysis of an organic compound gives formaldehyde as one of the products. This confirms the presence of :

In a face centred cubic lattice, atom A occupies the corner positions and atom B occupies the face centre positions. If one atom of B is missing from one of the face centred points, the formula of the compound is :

The degree of dissociation ($$\alpha$$ ) of a weak electrolyte, A_xB_y is related to van’t Hoff factor (i) by the expression :