Chemistry Quiz
Acids, bases, bonds and baking soda: 15 questions on the chemistry happening all around you.
What is the pH of pure water at room temperature?
Got a hunch? Pick the answer that feels right.
7
Pure water is neutral with a pH of 7 at 25 °C, because it contains equal tiny amounts of hydrogen and hydroxide ions. Values below 7 are acidic and values above 7 are alkaline, or basic.
The scale is logarithmic, so a drink at pH 2 is roughly ten times more acidic than one at pH 3 and a hundred times more acidic than one at pH 4.
Which gas makes up about 78 percent of the air we breathe?
Got a hunch? Pick the answer that feels right.
Nitrogen
Dry air is roughly 78 percent nitrogen, 21 percent oxygen and just under 1 percent argon, with carbon dioxide at only about 0.04 percent. Nitrogen gas is very unreactive, which is why it passes through our lungs unchanged.
Plants cannot use nitrogen gas directly; soil bacteria and lightning convert it into compounds that roots can absorb.
What is the chemical name for ordinary table salt?
Got a hunch? Pick the answer that feels right.
Sodium chloride
Table salt is sodium chloride, NaCl, an ionic compound of sodium and chlorine. Sodium is a metal that explodes in water and chlorine is a poisonous gas, yet bonded together they form the harmless crystals we sprinkle on food.
Iodized salt contains a trace of potassium iodide to prevent goiter, a thyroid condition caused by iodine deficiency.
What is it called when a solid turns directly into a gas without melting first?
Got a hunch? Pick the answer that feels right.
Sublimation
Sublimation happens when a solid gains enough energy to turn straight into vapor, skipping the liquid phase. Deposition is the reverse, gas straight to solid, which is how frost forms on a cold window.
Freeze drying uses sublimation: food is frozen and its ice is then pulled off as vapor under low pressure, preserving flavor and nutrients.
Which acid gives vinegar its sour taste?
Got a hunch? Pick the answer that feels right.
Acetic acid
Vinegar is a dilute solution of acetic acid, typically 4 to 8 percent, produced when bacteria ferment the alcohol in wine, cider or grain. Citric acid is found in lemons and lactic acid in sour milk.
The word vinegar comes from the French vin aigre, meaning sour wine, and balsamic vinegar is aged in wooden barrels for years to develop its flavor.
Which gas bubbles off when zinc reacts with hydrochloric acid?
Got a hunch? Pick the answer that feels right.
Hydrogen
Metals above hydrogen in the reactivity series displace it from acids: zinc plus hydrochloric acid gives zinc chloride and hydrogen gas. Holding a lit splint to the gas produces the squeaky pop that identifies hydrogen.
Carbon dioxide is what you get instead when an acid meets a carbonate, which is why vinegar fizzes on a piece of chalk.
What does a catalyst do in a chemical reaction?
Got a hunch? Pick the answer that feels right.
Speeds it up without being used up
A catalyst lowers the activation energy a reaction needs, so it proceeds faster, and it is left unchanged at the end to be used again. Enzymes are the biological catalysts that run the chemistry of living cells.
The catalytic converter in a car uses platinum, palladium and rhodium to turn toxic exhaust gases into less harmful ones.
What type of chemical bond forms when two atoms share a pair of electrons?
Got a hunch? Pick the answer that feels right.
Covalent bond
Covalent bonds hold atoms together by sharing electrons, as in water, methane and oxygen molecules. Ionic bonds form when electrons are transferred, creating oppositely charged ions that attract each other.
Diamond is a single giant network of carbon atoms joined by covalent bonds, which is why it is the hardest natural material.
Which household product has the chemical formula NaHCO3?
Got a hunch? Pick the answer that feels right.
Baking soda
Sodium bicarbonate, better known as baking soda, releases carbon dioxide when heated or mixed with an acid, which is what makes cakes rise. Washing soda is sodium carbonate and household bleach is sodium hypochlorite.
An open box of baking soda in the fridge absorbs odors because it neutralizes both acidic and basic smelly compounds.
Besides a salt, what is produced when an acid neutralizes a base?
Got a hunch? Pick the answer that feels right.
Water
In a neutralization reaction, hydrogen ions from the acid combine with hydroxide ions from the base to form water, while the remaining ions form a salt. Hydrochloric acid plus sodium hydroxide gives sodium chloride and water.
Antacid tablets work on the same principle, using a mild base to neutralize excess stomach acid.
Rusting is an everyday example of which type of chemical reaction?
Got a hunch? Pick the answer that feels right.
Oxidation
Rust forms when iron reacts with oxygen in the presence of water, losing electrons in an oxidation reaction to form hydrated iron(III) oxide. Painting or galvanizing keeps oxygen and water away from the metal.
Salt water speeds up rusting because the dissolved ions help carry electric charge between the iron and the oxygen.
What is dry ice?
Got a hunch? Pick the answer that feels right.
Solid carbon dioxide
Dry ice is carbon dioxide frozen at minus 78.5 °C (minus 109 °F). It is called dry because it sublimes straight to gas and leaves no puddle, which is why it makes the low fog used in stage shows.
Handle it with gloves: at that temperature it causes frostbite within seconds of touching bare skin.
What name is given to the amount of a substance containing 6.022 × 10²³ particles?
Got a hunch? Pick the answer that feels right.
A mole
The mole is the chemist's counting unit, defined by Avogadro's number of particles. One mole of carbon-12 atoms weighs 12 grams, which lets chemists convert between atomic masses and quantities they can weigh out.
Chemists celebrate Mole Day on October 23 between 6:02 am and 6:02 pm, a nod to 6.02 × 10²³.
Which law states that the volume of a gas is inversely proportional to its pressure at constant temperature?
Got a hunch? Pick the answer that feels right.
Boyle's law
Boyle's law, published by Robert Boyle in 1662, says that squeezing a gas into half the volume doubles its pressure if the temperature stays the same. Charles's law relates volume to temperature instead.
Divers must breathe out while ascending because Boyle's law means the air in their lungs expands as the pressure drops.
Which metal is extracted from bauxite ore?
Got a hunch? Pick the answer that feels right.
Aluminum
Bauxite is refined into aluminum oxide and then split by electrolysis in the Hall-Héroult process, which needs so much electricity that smelters are often built near cheap hydropower. Iron comes from ores such as hematite.
Recycling aluminum uses about 5 percent of the energy needed to make it from ore, so drink cans are among the most recycled items.
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All Science quizzes →About the Chemistry Quiz
Chemistry is everywhere: the acetic acid in vinegar, the fizz of hydrogen when zinc meets acid, and the dry ice that sublimes into stage fog without ever melting. Pure water sits at pH 7, the air you breathe is nearly four fifths nitrogen, and a single mole of anything contains more than 600 sextillion particles.
These 15 questions go beyond the periodic table into reactions, acids and bases, bonding, the states of matter and the everyday chemistry of kitchens and garages. The first few are easy wins, the middle covers school chemistry essentials, and the final questions on Boyle's law and metal extraction will stretch keen chemists. Great for students revising, teachers and trivia fans.
You will find 15 multiple choice questions here, each with four options. Difficulty: Medium. Most people finish in about 6 minutes, and every answer comes with a short explanation and one extra fact worth keeping.
How to play
Read the question and pick one of the four answers. The correct answer is revealed straight away with a short explanation, then press Next question to keep going. At the end you get your score out of 15 and a full review of your round. Play again any time and the questions arrive in a fresh order. There is no timer and no account.
Good to know before you play
Does this quiz cover the periodic table?
Only lightly. It focuses on reactions, acids and bases, bonding and states of matter, so it pairs well with the separate Periodic Table Quiz on the site.
Is it suitable for school students?
Yes. The questions match typical secondary school chemistry, and the explanations give the formulas and reasoning so you learn as you play.
What is the hardest question?
Most players stumble on the mole, Boyle's law and which ore aluminum comes from. The explanations cover all three in detail.
Answer key: all 15 questions with explanations
- What is the pH of pure water at room temperature?
7 Pure water is neutral with a pH of 7 at 25 °C, because it contains equal tiny amounts of hydrogen and hydroxide ions. Values below 7 are acidic and values above 7 are alkaline, or basic. The scale is logarithmic, so a drink at pH 2 is roughly ten times more acidic than one at pH 3 and a hundred times more acidic than one at pH 4. - Which gas makes up about 78 percent of the air we breathe?
Nitrogen Dry air is roughly 78 percent nitrogen, 21 percent oxygen and just under 1 percent argon, with carbon dioxide at only about 0.04 percent. Nitrogen gas is very unreactive, which is why it passes through our lungs unchanged. Plants cannot use nitrogen gas directly; soil bacteria and lightning convert it into compounds that roots can absorb. - What is the chemical name for ordinary table salt?
Sodium chloride Table salt is sodium chloride, NaCl, an ionic compound of sodium and chlorine. Sodium is a metal that explodes in water and chlorine is a poisonous gas, yet bonded together they form the harmless crystals we sprinkle on food. Iodized salt contains a trace of potassium iodide to prevent goiter, a thyroid condition caused by iodine deficiency. - What is it called when a solid turns directly into a gas without melting first?
Sublimation Sublimation happens when a solid gains enough energy to turn straight into vapor, skipping the liquid phase. Deposition is the reverse, gas straight to solid, which is how frost forms on a cold window. Freeze drying uses sublimation: food is frozen and its ice is then pulled off as vapor under low pressure, preserving flavor and nutrients. - Which acid gives vinegar its sour taste?
Acetic acid Vinegar is a dilute solution of acetic acid, typically 4 to 8 percent, produced when bacteria ferment the alcohol in wine, cider or grain. Citric acid is found in lemons and lactic acid in sour milk. The word vinegar comes from the French vin aigre, meaning sour wine, and balsamic vinegar is aged in wooden barrels for years to develop its flavor. - Which gas bubbles off when zinc reacts with hydrochloric acid?
Hydrogen Metals above hydrogen in the reactivity series displace it from acids: zinc plus hydrochloric acid gives zinc chloride and hydrogen gas. Holding a lit splint to the gas produces the squeaky pop that identifies hydrogen. Carbon dioxide is what you get instead when an acid meets a carbonate, which is why vinegar fizzes on a piece of chalk. - What does a catalyst do in a chemical reaction?
Speeds it up without being used up A catalyst lowers the activation energy a reaction needs, so it proceeds faster, and it is left unchanged at the end to be used again. Enzymes are the biological catalysts that run the chemistry of living cells. The catalytic converter in a car uses platinum, palladium and rhodium to turn toxic exhaust gases into less harmful ones. - What type of chemical bond forms when two atoms share a pair of electrons?
Covalent bond Covalent bonds hold atoms together by sharing electrons, as in water, methane and oxygen molecules. Ionic bonds form when electrons are transferred, creating oppositely charged ions that attract each other. Diamond is a single giant network of carbon atoms joined by covalent bonds, which is why it is the hardest natural material. - Which household product has the chemical formula NaHCO3?
Baking soda Sodium bicarbonate, better known as baking soda, releases carbon dioxide when heated or mixed with an acid, which is what makes cakes rise. Washing soda is sodium carbonate and household bleach is sodium hypochlorite. An open box of baking soda in the fridge absorbs odors because it neutralizes both acidic and basic smelly compounds. - Besides a salt, what is produced when an acid neutralizes a base?
Water In a neutralization reaction, hydrogen ions from the acid combine with hydroxide ions from the base to form water, while the remaining ions form a salt. Hydrochloric acid plus sodium hydroxide gives sodium chloride and water. Antacid tablets work on the same principle, using a mild base to neutralize excess stomach acid. - Rusting is an everyday example of which type of chemical reaction?
Oxidation Rust forms when iron reacts with oxygen in the presence of water, losing electrons in an oxidation reaction to form hydrated iron(III) oxide. Painting or galvanizing keeps oxygen and water away from the metal. Salt water speeds up rusting because the dissolved ions help carry electric charge between the iron and the oxygen. - What is dry ice?
Solid carbon dioxide Dry ice is carbon dioxide frozen at minus 78.5 °C (minus 109 °F). It is called dry because it sublimes straight to gas and leaves no puddle, which is why it makes the low fog used in stage shows. Handle it with gloves: at that temperature it causes frostbite within seconds of touching bare skin. - What name is given to the amount of a substance containing 6.022 × 10²³ particles?
A mole The mole is the chemist's counting unit, defined by Avogadro's number of particles. One mole of carbon-12 atoms weighs 12 grams, which lets chemists convert between atomic masses and quantities they can weigh out. Chemists celebrate Mole Day on October 23 between 6:02 am and 6:02 pm, a nod to 6.02 × 10²³. - Which law states that the volume of a gas is inversely proportional to its pressure at constant temperature?
Boyle's law Boyle's law, published by Robert Boyle in 1662, says that squeezing a gas into half the volume doubles its pressure if the temperature stays the same. Charles's law relates volume to temperature instead. Divers must breathe out while ascending because Boyle's law means the air in their lungs expands as the pressure drops. - Which metal is extracted from bauxite ore?
Aluminum Bauxite is refined into aluminum oxide and then split by electrolysis in the Hall-Héroult process, which needs so much electricity that smelters are often built near cheap hydropower. Iron comes from ores such as hematite. Recycling aluminum uses about 5 percent of the energy needed to make it from ore, so drink cans are among the most recycled items.
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