Atoms and reactions — Intermediate

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Level 2: Intermediate

Explain, apply, analyse, sequence — connect ideas, read patterns, use rules in new contexts (bridge to Year 11).

1. In the shell model, moving down a group usually means:

   A)One fewer occupied shell at each stepB)The same shell number for the outer electronsC)An extra occupied shell is addedD)The nucleus loses protons

2. A large difference in electronegativity usually suggests bonding that is more:

   A)Covalent because electrons are shared equallyB)Ionic because electron transfer is more likelyC)Metallic because electrons become delocalisedD)Unstable because no attraction can form

3. Why does atomic radius usually increase down a group?

   A)Nuclear charge falls to zeroB)More occupied shells place outer electrons farther outC)Valence electrons move into the nucleusD)Atoms lose electrons as you move downward

4. Across a period from left to right, atomic radius tends to:

   A)Decrease as stronger nuclear attraction pulls on the same shellB)Increase because each element gains a new shellC)Stay the same because period number is fixedD)Change randomly with no trend

5. Ionisation energy often increases across a period because outer electrons:

   A)Move into a new shell at each stepB)Feel less attraction from the nucleusC)Become farther from the nucleusD)Feel stronger attraction from the nucleus

6. Metallic bonding is best described as:

   A)Shared electron pairs between two atoms onlyB)Positive ions with no mobile electronsC)A lattice of cations attracted to delocalised electronsD)Neutral atoms held together by weak forces only

7. Ionic bonding is best described as:

   A)Shared pairs of electrons between atomsB)A sea of electrons around neutral atomsC)Dipole attractions between molecules onlyD)Electrostatic attraction between cations and anions

8. Why do halogens often gain one electron in ionic reactions?

   A)They usually lose one electron most easilyB)They are one electron short of a full outer shellC)They always lose seven electrons firstD)They cannot form ions any other way

9. Noble gases are relatively unreactive mainly because:

   A)They contain no electronsB)They are all metalsC)Their outer shell is already fullD)Their atoms are too massive to collide

10. In the activity series, a more reactive metal placed in a solution of a less reactive metal ion may:

    A)Displace the less reactive metal from its compoundB)Stay unchanged because all dissolved ions block the surfaceC)Turn into a noble gas before reactingD)React only with the solid container

11. Classify the reaction $\text{CaCO}_{3} \rightarrow \text{CaO} + \text{CO}_{2}$.

    A)SynthesisB)DecompositionC)Single displacementD)Double displacement

12. For $\text{Mg} + \text{O}_{2} \rightarrow \text{MgO}$, the smallest whole-number coefficient in front of $\text{MgO}$ in a balanced equation is:

    A)2B)1C)3D)4

13. Increasing the concentration of a solution often increases reaction rate because:

    A)Particles move more slowly but react betterB)There are fewer collisions, but each is strongerC)More particles per unit volume cause more collisionsD)Extra catalyst appears automatically

14. Powdered zinc reacts faster with acid than a single zinc lump mainly because the powder has:

    A)A higher molar massB)More exposed surface areaC)A higher concentrationD)A lower activation energy

15. Powdered chalk reacts more slowly with dilute acid than powdered zinc under similar conditions mainly because:

    A)Chalk must have a larger surface areaB)Zinc is more reactive with acid than chalkC)Chalk acts as a catalyst for zincD)Acid cannot react with carbonates

16. Activation energy is the:

    A)Energy stored in the products after reactionB)Minimum energy needed for a successful collisionC)Same quantity as the overall energy changeD)Amount of heat released by the reaction

17. Heating a reaction increases the fraction of collisions that exceed activation energy because particles:

    A)Grow larger as they warmB)Spend more time stationaryC)Create catalyst automaticallyD)Move faster and have a wider spread of energies

18. A student says exothermic reactions always have lower activation energy than endothermic reactions. The best response is:

    A)Correct, because both ideas describe the same quantityB)Correct, because releasing heat removes the barrierC)Incorrect, because energy change and activation energy describe different ideasD)Incorrect, because endothermic reactions have no activation energy

19. A double displacement reaction often occurs when:

    A)One free element replaces another in a compoundB)One compound breaks into simpler substancesC)A gas always forms from a single reactantD)Ions exchange partners and form a new product

20. In a neutralisation reaction, water forms when:

    A)Two neutral molecules collide with no ions presentB)A metal atom gives its electrons to oxygenC)$\text{H}^{+}(aq)$ reacts with $\text{OH}^{-}(aq)$D)Every product leaves the beaker as a gas

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