The following tautomerism has been observed. Add any non-bonding electrons. Use arrows to push electrons and show how the structure on the left can be transformed to the structure on the right. Which side of the equilibrium is favored? Why?
(see diagram in attached file)
For these types of questions you need to try and get a lot of evidence. One of the best ways to figure out this is to try and find Ka values. Ka values are all about acidity, ...
An explanation of the favoring of equilibrium on a tautomerism.