Atoms and reactions — Advanced

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Level 3: Advanced

Evaluate, justify, synthesise, propose — combine ideas, judge claims and methods (senior secondary style).

1. After heating one trial, a student sees the reaction run faster and concludes that temperature is the only factor that matters. Which reply is best?

   A)The conclusion is secure because one faster trial proves temperature is the only causeB)The conclusion is secure if the graph looks smooth during that one runC)The conclusion is too strong because other factors still matter and must be controlledD)The conclusion is wrong because temperature never affects collision frequency or energy

2. Reactive metals are often stored under oil or inert gas mainly to:

   A)Reduce contact with air and moisture that would react with the metalB)Lower the metal temperature until reactions become impossibleC)Dissolve the oxide layer so the metal stays shinyD)Remove nitrogen so only noble gases can collide with the surface

3. A student wants to identify one compound in a mixture using only melting point. What is the sharpest weakness in that plan?

   A)A single melting point always identifies one compound with certaintyB)Different substances can have similar melting points, so more evidence is neededC)Only ionic compounds have useful melting pointsD)Any sharp melting point proves the sample cannot be a mixture

4. A lab group wants a greener synthetic route. Which choice best fits that goal?

   A)Use excess reagent so the reaction finishes quickly, even if more waste remainsB)Use the hottest conditions available so each run takes less timeC)Avoid catalysts so the procedure includes fewer substances overallD)Use a catalyst, milder conditions, and a route that produces less hazardous waste

5. A student claims: Because the reaction is exothermic, it must be instantaneous. Which evaluation is best?

   A)Correct, because releasing heat means the reaction barrier must be zeroB)Correct, because all exothermic reactions finish quickly in the labC)Incorrect, because reaction rate depends on pathway and activation energy as wellD)Incorrect, because exothermic reactions can happen only when energy is supplied first

6. For $\text{CH}_{4} + \text{O}_{2} \rightarrow \text{CO}_{2} + \text{H}_{2}\text{O}$, balanced coefficients show mole ratios on paper. Which statement about an actual burn is most accurate?

   A)The balanced equation becomes invalid whenever the fuel contains carbonB)The burn still needs enough oxygen, mixing, and ignition as well as the right ratioC)A methane flame shows that water cannot be one of the productsD)Once the coefficients balance, there is no need to think about conditions

7. In some demonstrations, nanoparticle catalysts outperform bulk metal mainly because nanoparticles:

   A)Heat the mixture more strongly as soon as they are addedB)Remove activation energy from every reaction entirelyC)Stop reactants diffusing through the liquidD)Expose much more surface area per gram of catalyst

8. Linking periodic trends to metal reactivity, which statement is most accurate?

   A)Metals cannot lose electrons during redox reactionsB)Reactivity is unrelated to how far outer electrons are from the nucleusC)Down Group 1, outer electrons are farther out, so alkali metals often become more reactiveD)Across a period, metallic character increases steadily toward the halogens

9. You use gas volume versus time to study reaction rate. Which statement gives the best main idea and caution?

   A)Gas volume can track gas amount if temperature and pressure are controlled or corrected forB)Gas volume cannot be used to compare rates in school experimentsC)Gas traces are too noisy to show any useful trendD)Only colour change can be used as a rate measure

10. Using flame colour alone to identify an unknown metal ion is best described as:

    A)Reliable because each common ion has a unique flame colour in all casesB)Reliable because the colour comes from black-body radiation, not the ionC)Risky because colours can overlap and contamination can mislead the resultD)Invalid because flame tests identify anions rather than metal ions

11. A metal from the far left of the periodic table reacting with a non-metal from the far right most often forms:

    A)A noble-gas moleculeB)A giant covalent networkC)No stable compound at allD)An ionic compound made of cations and anions

12. A student claims: If a reaction is slow at room temperature, it must be endothermic. Which reply is best?

    A)Correct, because all slow reactions absorb heat overallB)Incorrect, because rate depends on activation energy and pathway, not only energy changeC)Incorrect, because a slow reaction cannot occur at room temperatureD)Correct, because activation barriers exist only in endothermic reactions

13. When diluting concentrated acid, add acid to water rather than water to acid mainly because:

    A)Both orders release the same heat and pose the same splash riskB)Water always sinks below concentrated acid before mixingC)The dilution is very exothermic, and adding acid to water reduces local overheating and splashingD)The acid must briefly boil before it can be diluted safely

14. The claim that nanomaterials are always safer than bulk materials because less mass is used is:

    A)True, because lower mass always means lower hazardB)True, because particle size does not affect uptake or exposureC)False, because very high surface area can change behaviour and riskD)False, because nano and bulk forms behave identically in all tests

15. A class wants to test whether a catalyst changes the rate of hydrogen peroxide decomposition. Which plan is the fairest test?

    A)Use one warm flask without catalyst and one cool flask with catalystB)Use the same volumes, concentration, and temperature, adding catalyst to only one flaskC)Use different peroxide concentrations so both flasks finish at the same timeD)Add more catalyst to the flask that has less peroxide to balance the mass

16. A student mixes acid with marble chips in an open flask and the measured mass falls. Which explanation is best?

    A)Mass is conserved, but carbon dioxide escaped so the balance no longer measured the whole systemB)Atoms were destroyed when the gas bubbles formedC)Some of the mass changed completely into heatD)The solid products must weigh less than the reactants

17. Powdered magnesium reacts faster than a magnesium ribbon in acid. Which conclusion is best?

    A)The powder is a different element higher in the activity seriesB)The faster rate proves the powder releases more energy per moleC)The ribbon cannot react because metals must be powdered firstD)The powder has more surface area, so faster rate does not by itself prove greater reactivity

18. Two clear solutions are mixed and the beaker turns cloudy. Which extra observation best supports the claim that a precipitate formed?

    A)The beaker feels cooler than beforeB)A solid can be collected by filtration and remains after dryingC)The liquid conducts electricity after mixingD)A few bubbles appear at the surface

19. A student gets a yellow flame test and wants to identify the ion with more confidence. What is the best next step?

    A)Repeat the same flame test with a bigger flame onlyB)Assume sodium immediately because yellow is always uniqueC)Use a clean wire and combine the flame test with another ion testD)Ignore contamination because flame colours cannot overlap

20. A steel fence is protected by a zinc coating. Which explanation best fits the activity series?

    A)Zinc is more reactive, so it can oxidise first and protect exposed ironB)Zinc is less reactive, so oxygen reacts with iron only after zinc dissolvesC)Zinc stops all electron transfer because touching metals cannot oxidiseD)Zinc protects iron only because it conducts heat better

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