Multiple choice Which chemical produces tears when vacuoles of onion are broken? 1-propenesulfenic acid Syn-propanethial-S-oxide Ellagic acid Theaflavin-3-gallate Reveal answer Fill a bubble to check yourself B Correct answer Explanation Syn-propanethial-S-oxide is formed by the action of lachrymatory factor synthase (LFS) on 1-propensulfenic acid and produces tears in eyes.