Why does tape lose stickiness over time?

Answer: Adhesive dries and hardens

Adhesive dries and hardens ✓ — Correct! Tape adhesive slowly oxidizes and loses its flexibility. UV light and heat speed up this process. The once-soft, tacky adhesive becomes hard and brittle, losing its ability to form bonds with surfaces.

Tape evaporates slowly into air — Wrong. Tape doesn't evaporate—it's a solid. The loss of stickiness comes from chemical breakdown of the adhesive, not physical disappearance.

Tape stretches too thin — Wrong. Tape thickness doesn't significantly change. The adhesive's chemical properties degrade over time.