Q.Comment on the nature of two S-O bonds formed in SO2 molecule. Are the two S-O bonds in this molecule equal ?

Step 1 — Lewis/resonance structures of $SO_2$.

$SO_2$ can be drawn with two major resonance structures, each showing one S=O double bond and one S→O bond (dative/single bond with a formal charge arrangement), with the double bond alternating between the two oxygens:

Step 2 — Effect of resonance.

Because these structures are equivalent in energy and interconvert by simple electron delocalisation, the true structure is a resonance hybrid where the π-electron density is shared equally between both S–O bonds.

Step 3 — Consequence for bond nature. …

Draw both resonance structures of $SO_2$, note they are equivalent/degenerate, and conclude that the true (hybrid) structure must have identical, intermediate-order bonds — r …

• Don't describe $SO_2$ as having "one single and one double bond" as the final answer — that describes only a single resonance contributor; the actual molecule has two equivalent, intermediate bonds. …