Which among the above compound/s does/do not form Silver mirror...

Aldehyde, alpha-hydroxy ketone and hemiacetals give positive Tollen's test. Enol which can get converted into aldehyde through tautomerism are also give positive Tollen's test.

$( I )$ is aldehyde, $( II )$ get converted into ketones through tautomerism, $( III )$ get converted into aldehyde through tautomerism and $( IV )$ is hemiacetal so, $( II )$ will not give positive Tollen's test.