Write the tautomerism in sulphurous acid.

Explanation

Sulphurous acid has two tautomeric forms.
`underset("(I)")(O=underset(OH)underset("| ")"S "-O)hharr underset("(II)")(HK-overset(H)overset(|)underset(O)underset(||)S=O)`
Structure I is prefereed as the sulphite `(SO_(3)^(2-))` salts are familier for sulphurous acid.