What is the passage mainly about?

Why cutting an onion makes a gas that stings the eyes. (The passage follows one chain from the knife to the tears. The knife and the tears are steps in that chain, not the subject.)

According to the passage, what happens when a knife breaks the walls inside an onion?

Two things that were kept apart meet and make a gas. (The second paragraph says the two were kept apart in separate rooms, the knife breaks the walls, and then they meet and make a new gas.)

In this passage, a "reaction" is

a change that happens when two things meet (The passage has already shown two things meeting and making something new. When cold "slows the whole reaction down," the reaction is that change.)

The passage suggests that how much your eyes sting depends on

how much gas escapes from the cut onion (A sharp knife lets less gas escape and it helps. Turn that around: more gas means more sting. Size, storage, and the table are never mentioned.)

Why Onions Make You Cry: Level 1 Reading Comprehension Questions

An onion on the table is quiet. Cut it, and your eyes sting within seconds. The onion is not doing this to you. It is defending itself, and you are standing too close.

Inside an onion, two things are kept apart in separate rooms. One is a chemical the plant has stored. The other is a tool that changes it. A knife breaks the walls between them. They meet, and the onion makes a new gas that rises into the air.

The gas reaches your eye. There it meets the thin layer of water on the surface and turns into a weak acid. Your eye feels the sting and does the only thing it can. It makes tears to wash the acid away.

This is why a sharp knife helps. It cuts the cells instead of crushing them, so less gas escapes. A cold onion helps too. Cold slows the whole reaction down.

Comprehension questions