Atoms and reactions — Intermediate

Score: 0 / 10

Level 2: Intermediate

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

1. Why does atomic radius tend to increase down a group?

   A)Each step adds protons without adding electron shells, so outer electrons are pulled inB)Additional electron shells increase size despite increasing nuclear chargeC)Nuclear charge stays the same down a group, so size changes are randomD)Valence electrons occupy the same principal shell number, so radius should be almost constant

2. Classify: $\text{CaCO}_3 \rightarrow \text{CaO} + \text{CO}_2$.

   A)SynthesisB)DecompositionC)Single displacementD)Double displacement only

3. Increasing concentration of solutions often increases rate because:

   A)Higher concentration lowers average particle speed, so only high-energy collisions occurB)Collisions become less frequent but each collision transfers more energyC)More reactant particles per unit volume tend to collide more frequentlyD)Concentration changes how much catalyst is present, which is the sole rate factor

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

   A)Undergo displacement (metal ion reduced, more reactive metal oxidised)—if conditions allowB)Always remain unreactive because the salt prevents any electron transferC)Only reduce water if the less reactive ion is a spectator in all casesD)Preferentially dissolve the less reactive metal as a free element

5. Ionisation energy: energy to remove an outer electron. It often increases across a period (left to right) because:

   A)Atoms gain new outer shells each step across a period, shielding valence electrons moreB)Nuclear charge decreases while electron number stays fixedC)Atomic radius grows steadily across a period, weakening attraction to the nucleusD)Effective nuclear attraction on valence electrons tends to increase

6. Powdered zinc reacts faster with acid than a single lump mainly due to:

   A)Powdered zinc has a higher average molar mass, so more moles react per gramB)More surface area for acid–solid contact and collisionsC)The acid’s concentration effectively drops when in contact with a smaller lumpD)Powder stores thermal energy that the lump lacks, lowering activation energy

7. Metallic bonding is best described as:

   A)Shared pairs between two specific atoms onlyB)Ions locked in a lattice with no mobile electronsC)A sea of delocalised electrons holding positive metal ions togetherD)Only covalent bonds between metal atoms

8. Across a period (left to right), atomic radius tends to:

   A)Decrease as nuclear charge pulls valence electrons more strongly (same shell trend)B)Increase steadily because shells are added each stepC)Stay exactly constantD)Depend only on group number, not period

9. A double displacement reaction often occurs when:

   A)One element replaces another in a compound onlyB)A single compound splitsC)Only gases formD)Ions exchange partners to form a precipitate, gas or molecular product (where conditions allow)

10. Activation energy is:

    A)The total energy of all productsB)The minimum energy needed for a successful collision leading to reactionC)Always zero for exothermic reactionsD)The same as enthalpy change only

← Back to hub