What is tautomerism ? Give two examples.

Explanation

Tautomerism is a phenomenon in which a single compound exists in two readily interconvertible forms, which differs distinctly in the relative position of at least one atomic nucleus, usually hydrogen. For example, Hydrocyanic acid (HCN) exists in the following tautomeric forms.
`underset("Hydrocyanic acid")(N-C -= N) hArr underset("Isohydrocyanic acid")(H- N overset(rarr)= C)`