A powerful eye irritant in smoke is

Correct answer: (d) Peroxyacetyl nitrate

Explanation

Peroxyacetyl nitrate (PAN) is a secondary pollutant of photochemical smog and a powerful eye irritant (lachrymator).

It is thermally unstable, decomposing into peroxy radicals and nitrogen dioxide.

Distractors: SO₂ irritates lungs, CO₂ is a greenhouse gas, ozone shields UV.