Chemical Reactions & Equations Quiz

1. What is a chemical reaction?

1. A change in physical state such as melting
2. A process where atoms are rearranged, breaking and forming chemical bonds to produce new substances
3. The dissolving of a solid in liquid
4. The mixing of two substances without any change

2. What are the signs that a chemical reaction has taken place?

1. Only a change in temperature
2. Only colour change
3. Only the formation of a gas
4. Temperature change, gas production, colour change, precipitate formation, or light/sound emission

3. What is the law of conservation of mass in chemistry?

1. Mass increases in exothermic reactions
2. Mass is created during reactions
3. Some atoms are destroyed in reactions
4. The total mass of reactants equals the total mass of products in a chemical reaction

4. Balance this equation: H₂ + O₂ → H₂O

1. 2H₂ + O₂ → 2H₂O
2. 4H₂ + O₂ → 2H₂O
3. H₂ + 2O₂ → 2H₂O
4. H₂ + O₂ → H₂O

5. What type of reaction is: acid + base → salt + water?

1. Combustion
2. Decomposition
3. Neutralisation
4. Oxidation

6. What is combustion?

1. A rapid reaction between a fuel and oxygen that releases heat and light
2. The decomposition of a compound by heat
3. The dissolving of a metal in acid
4. The reaction of a metal with water

7. What is an exothermic reaction?

1. A reaction involving explosions
2. A reaction that absorbs heat from surroundings
3. A reaction that only occurs at high temperatures
4. A reaction that releases energy (heat) to surroundings

8. What is the chemical test for hydrogen gas?

1. It produces a squeaky pop with a burning splint
2. It relights a glowing splint
3. It turns limewater milky
4. It turns litmus paper blue

9. What is the chemical test for carbon dioxide?

1. It produces a squeaky pop with a lit splint
2. It relights a glowing splint
3. It turns damp litmus paper red
4. It turns limewater milky

10. What is an acid in terms of protons (Brønsted-Lowry definition)?

1. A substance that accepts protons (H⁺ ions)
2. A substance that donates protons (H⁺ ions)
3. A substance that produces OH⁻ ions
4. A substance with a pH above 7

11. What is produced when a metal reacts with an acid?

1. A base and oxygen
2. A salt and hydrogen gas
3. Carbon dioxide and water
4. Metal oxide and water

12. What type of reaction is: 2H₂O₂ → 2H₂O + O₂?

1. Combustion
2. Decomposition
3. Displacement
4. Synthesis

13. What is a catalyst?

1. A product of a chemical reaction
2. A substance consumed in a reaction to make it go faster
3. A substance that speeds up a reaction without being used up
4. An energy source for reactions

14. What is the pH scale?

1. A scale from 0–14 measuring how acidic or alkaline a substance is
2. A scale from 0–7 measuring acidity only
3. A scale measuring temperature of reactions
4. A scale measuring the concentration of salts

15. What type of reaction is: Fe + CuSO₄ → FeSO₄ + Cu?

1. Combustion
2. Decomposition
3. Displacement
4. Neutralisation

16. What is the word equation for the complete combustion of methane?

1. Methane → carbon + hydrogen
2. Methane + oxygen → carbon + water
3. Methane + oxygen → carbon dioxide + water
4. Methane + oxygen → carbon monoxide + hydrogen

17. What is precipitation in chemistry?

1. The decomposition of a compound
2. The dissolving of a solid in water
3. The evaporation of a solution
4. The formation of an insoluble solid when two solutions are mixed

18. What does 'activation energy' mean?

1. The energy released in a reaction
2. The energy stored in chemical bonds
3. The minimum energy required to start a chemical reaction
4. The temperature at which a reaction occurs

19. What is oxidation in terms of electron transfer?

1. Gain of electrons
2. Gain of protons
3. Loss of electrons
4. Loss of protons

20. What is the chemical formula for sulfuric acid?

1. H₂SO₄
2. H₃PO₄
3. HCl
4. HNO₃