Atoms and reactions — Foundational

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Level 1: Foundational

Identify, describe, state, calculate — recall facts and use standard relationships (typical early Year 10).

1. The atomic number of an element is the number of:

   A)Neutrons in the nucleus onlyB)Protons in the nucleusC)Electrons in the outer shell onlyD)Protons plus neutrons in the nucleus

2. In a neutral atom, the number of electrons equals:

   A)The number of protons in the nucleusB)Zero for every neutral atomC)The number of neutrons onlyD)Twice the mass number

3. The mass number of an atom is the total number of:

   A)Protons onlyB)Electrons onlyC)Protons and neutronsD)Valence electrons only

4. Isotopes of the same element differ in their number of:

   A)ProtonsB)Valence electronsC)NeutronsD)Shells

5. Elements in the same group often have similar chemical properties because they have the same number of:

   A)Neutrons in the nucleusB)Valence electronsC)Occupied shellsD)Nucleons

6. In a Bohr-style shell model, electrons occupy:

   A)One continuous cloud with no levelsB)Discrete shells or energy levelsC)The nucleus with the protonsD)Positions unrelated to energy

7. A covalent bond involves:

   A)Shared electron pairs between atomsB)Transfer of all electrons to one atomC)A sea of delocalised electronsD)Repulsion between positive ions

8. The relative atomic mass shown on the periodic table is best described as:

   A)The mass number of the lightest isotope onlyB)A weighted average of isotope massesC)The number of neutrons in the atomD)The mass of one single atom in every sample

9. Endothermic means that, overall:

   A)No energy is transferred during the changeB)Energy leaves the system and enters the surroundingsC)Reaction rate alone decides the energy changeD)Energy enters the system from the surroundings

10. A combustion reaction of a hydrocarbon in oxygen typically produces $\text{CO}_{2}$ and:

    A)$\text{N}_{2}$B)Solid carbon onlyC)$\text{H}_{2}\text{O}$D)$\text{CO}$ only

11. Conservation of mass in a closed reaction system means that:

    A)Atoms disappear when a gas formsB)Atoms rearrange, but total mass stays the sameC)Mass changes into heat in every reactionD)Only solids count toward the total mass

12. A precipitate is:

    A)A new solid formed in a solutionB)A gas bubble rising through a liquidC)A colour change with no new substanceD)A dissolved ion that stays invisible

13. A reaction in which one compound breaks into simpler substances is called:

    A)SynthesisB)DecompositionC)Single displacementD)Combustion

14. $2\text{H}_{2} + \text{O}_{2} \rightarrow 2\text{H}_{2}\text{O}$ is best classified as:

    A)SynthesisB)DecompositionC)Single displacementD)Double displacement

15. A single displacement reaction usually has the pattern:

    A)One compound forming one product onlyB)Two compounds swapping ionsC)An element plus a compound forming a new element and a new compoundD)Atoms staying in the same substances

16. In a chemical equation, state symbols such as $(aq)$ and $(s)$ show:

    A)Whether the reaction is exothermic or endothermicB)The physical state of each substanceC)Which substance is the catalystD)How fast the reaction will happen

17. Which change commonly increases the rate of a reaction involving a solid?

    A)Using one large lumpB)Using a powder with greater surface areaC)Lowering the temperatureD)Removing collisions between particles

18. A catalyst speeds up many reactions by:

    A)Being used up each time it worksB)Removing reactant particles from the mixtureC)Lowering particle kinetic energyD)Providing a pathway with lower activation energy

19. Increasing temperature often speeds reactions because particles:

    A)Collide more often and with more energyB)Stop moving once the flask warms evenlyC)Have less kinetic energy at higher $T$D)Need fewer collisions to react

20. For many gas-phase reactions, increasing pressure can increase rate because particles:

    A)No longer need activation energyB)Move more slowlyC)Turn into catalystsD)Are closer together and collide more often

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