Onions contain amino acid sulfoxides. when u cut an onion it separates and releases and it makes u cry
the onions contains sulphur compounds which pain our eyes .and then lacrimal glands in our eyes produce tears.but there are no such compounds in tomatoes .
thats the reason why we get tears from our eyes when we cut onions but it doesnt happen when we cut tomatoes.
your answer is correct....just to elaborate it further...When you cut an onion, you break cells, releasing their contents. Amino acid sulfoxides form sulfenic acids. Enzymes that were kept separate now are free to mix with the sulfenic acids to produce propanethiol S-oxide, a volatile sulfur compound that wafts upward toward your eyes. This gas reacts with the water in your tears to form sulfuric acid. The sulfuric acid burns, stimulating your eyes to release more tears to wash the irritant away