Gases and Common Compounds

What do the air you breathe out, the lightest element, and the gas that keeps you alive all have in common? They each get their own quiz in this look at everyday gases.

Carbon Dioxide, Hydrogen, and Oxygen

Separate quizzes cover carbon dioxide (CO₂), hydrogen, and oxygen, mixing fill-in-the-blank with true or false items. You will look at where each gas comes from, how it behaves, and why it matters, including how trees take in CO₂ and why too much of it can be dangerous. With oxygen, you will see how plants release it as a by-product of photosynthesis and why it bonds so readily with other elements. The questions stay grounded in things you can picture rather than abstract theory.

Most of these sets are pitched at a beginner level, so they are a comfortable place to start in chemistry. You will come away knowing the basic personality of three of the most important gases around us.

Did You Know?

Solid carbon dioxide, better known as dry ice, never melts into a puddle. It skips the liquid stage entirely and turns straight from a solid into a gas, a change called sublimation.

Hydrogen got its name for a good reason too. The word means "water maker," which makes sense once you learn that burning hydrogen produces H₂O, plain water.

How the Quizzes Work

Each gas gets a short quiz of about five minutes, and you can revisit any of them whenever you want the facts to settle in. Tackling one gas at a time keeps things clear instead of overwhelming. If you have ever wondered why a fire needs air or why soda fizzes, these gases are behind the answers. Ready to get to know the air around you? Try the free interactive chemistry quizzes and pick a gas to start with.

3. Carbon Dioxide

This 11-question quiz looks at carbon dioxide, the gas we breathe out and plants take in. You will answer fill-in-the-blank and true or false items, with prompts such as What is the solid form of carbon dioxide? and Carbon dioxide is absorbed by trees and plants during ___. One of the more surprising facts is that the solid form, known as dry ice, skips the liquid stage entirely and turns straight into a gas, a change called sublimation. You will also touch on where the gas comes from and why it can be dangerous in large amounts. Recommended level: intermediate.

score: 84% (everyone)

11 questions

8. Hydrogen

This 12-question quiz covers the basics of hydrogen, the first element on the periodic table, and it works well if you are just getting started in chemistry. You will answer a mix of fill-in-the-blank and true or false items, such as What is the atomic number of hydrogen? and Hydrogen produces ___ when burned. One detail that catches a lot of students off guard is what the name actually means. Hydrogen translates to "water maker," which makes sense once you see that burning it produces water. Recommended level: beginner.

score: 80% (everyone)

12 questions

10. Oxygen

Oxygen keeps us alive, and this 11-question quiz takes a closer look at what it actually is and how it behaves. Expect fill-in-the-blank prompts like Oxygen is the by-product of ___. alongside true or false checks about its color, taste, and the elements it bonds with. Here is something many learners do not expect: the word oxygen means "acid producer." Scientists once believed oxygen was part of every acid, which turned out to be wrong, but the name stuck anyway. Recommended level: beginner.

score: 76% (everyone)

11 questions