Chemistry questions and solutions

Browse original practice and official past-paper questions. Each question has its own link, with its source and worked solution.

364 questions · Page 7 of 16

1. Q1 · 2021 QCAA · Paper 1 · 1 mark
   QUESTION 1 Melting is a (A) physical change that is reversible. (B) chemical change that is reversible. (C) physical change that is irreversible. (D) chemical change that is irreversible.
   Chemical equilibrium
2. Q2 · 2021 QCAA · Paper 1 · 1 mark
   QUESTION 2 Intra-chain hydrogen bonding between peptide groups occurs in (A) primary protein structures. (B) secondary protein structures. (C) tertiary protein structures. (D) quaternary protein structures.
   Polymers and biomolecules
3. Q3 · 2021 QCAA · Paper 1 · 1 mark
   QUESTION 3 Predict which product is formed at the positive electrode when a 0.1 M aqueous solution of copper(II) sulfate is electrolysed using carbon electrodes. (A) Cu(s) (B) H2(g) (C) O2(g) (D) SO2(g)
   Redox and electrochemistry
4. Q4 · 2021 QCAA · Paper 1 · 1 mark
   QUESTION 4 The cleaning action of soap is impaired in hard water because the (A) hydrophilic end reacts with calcium ions to form insoluble salts. (B) hydrophobic end reacts with calcium ions to form insoluble salts. (C) hydrophilic end reacts with calcium ions to form insoluble fatty acids. (D) hydrophobic end reacts with calcium ions to form insoluble…
   Organic chemistry
5. Q5 · 2021 QCAA · Paper 1 · 1 mark
   QUESTION 5 A 10.0 M solution of ethanoic acid is best described as a (A) dilute solution of a weak acid. (B) dilute solution of a strong acid. (C) concentrated solution of a weak acid. (D) concentrated solution of a strong acid.
   Acids, bases and titration
6. Q6 · 2021 QCAA · Paper 1 · 1 mark
   QUESTION 6 Which type of atoms would be more likely to gain electrons based on its position in the periodic table? (A) halogens (B) noble gases (C) alkali metals (D) alkaline earth metals
   Redox and electrochemistry
7. Q7 · 2021 QCAA · Paper 1 · 1 mark
   QUESTION 7 Identify which molecule is an amide. (A) CH3CH2CN (B) CH3CH2NH2 (C) NH4CH3COO (D) CH3CONHCH3
   Organic chemistry
8. Q8 · 2021 QCAA · Paper 1 · 1 mark
   QUESTION 8 Electric current e– Air in e– Fuel in e– O2 and other gases in e– H+ H2 O2 H+ H2O Unused Excess fuel gases out Anode Electrolyte Cathode Identify the operating conditions for the hydrogen fuel cell. (A) acidic conditions with hydrogen given off as an unused gas (B) alkaline conditions with hydrogen given off as an unused gas (C) acidic conditions…
   Chemical synthesis
9. Q9 · 2021 QCAA · Paper 1 · 1 mark
   QUESTION 9 The boiling points of methane, ethane and propane increase as the lengths of the carbon chains increase because more energy is required to overcome the (A) intramolecular hydrogen bonds. (B) intermolecular hydrogen bonds. (C) intramolecular dispersion forces. (D) intermolecular dispersion forces.
   Organic chemistry
10. Q10 · 2021 QCAA · Paper 1 · 1 mark
    QUESTION 10 Determine which system at equilibrium will shift to the right (products) if the total pressure on the system is increased. (A) N2O4(g)  ⇌  2NO2(g) (B) 2H2O(g)  ⇌  2H2(g) + O2(g) (C) 2SO2(g) + O2(g)  ⇌  2SO3(g) (D) CO(g) + H2O(g)  ⇌  CO2(g) + H2(g)
    Chemical equilibrium
11. Q11 · 2021 QCAA · Paper 1 · 1 mark
    QUESTION 11 Enzymes can act as biological catalysts because they (A) can be denatured. (B) lower the activation energy. (C) are sensitive to pH and temperature changes. (D) increase the equilibrium constant for the reaction.
    Chemical equilibrium
12. Q12 · 2021 QCAA · Paper 1 · 1 mark
    QUESTION 12 Green chemistry principles include the design of chemical synthesis processes that (A) use renewable raw materials and minimise unwanted products. (B) use renewable raw materials and minimise unwanted reactants. (C) use non-renewable raw materials and minimise unwanted products. (D) use non-renewable raw materials and minimise unwanted reacta…
    Chemical synthesis
13. Q13 · 2021 QCAA · Paper 1 · 1 mark
    QUESTION 13 Infrared spectrum 1.0 0.8 Relative transmittance 0.6 0.4 0.2 0.0 3000 2000 1000 Wavenumber (cm –1) Determine the functional group present in the infrared spectrum. (A) ester (B) ketone (C) alcohol (D) carboxylic acid
    Organic analysis
14. Q14 · 2021 QCAA · Paper 1 · 1 mark
    QUESTION 14 Ka value Acid Ka = 4.00 × 10–4 Nitrous acid Ka = 1.76 × 10–5 Ethanoic acid Ka = 7.20 × 10–4 Hydrofluoric acid Ka = 1.40 × 10–3 Chloroethanoic acid Analyse the data to determine the relative strengths of acids from strongest to weakest. (A) chloroethanoic, ethanoic, nitrous, hydrofluoric (B) chloroethanoic, hydrofluoric, nitrous, ethanoic (C) etha…
    Acids, bases and titration
15. Q15 · 2021 QCAA · Paper 1 · 1 mark
    QUESTION 15 Which organic compound has the highest boiling point? (A) CH3(CH2)3CH3 (B) CH3(CH2)3CHO (C) CH2CH(CH2)2CH3 (D) CH3(CH2)3CH2OH
    Organic chemistry
16. Q16 · 2021 QCAA · Paper 1 · 1 mark
    QUESTION 16 Calculate the percentage yield of magnesium ethanoate when 8.0 moles of ethanoic acid reacts with 6.0 moles of magnesium carbonate, producing 3.5 moles of magnesium ethanoate as shown in the equation. 2CH3COOH(aq) + MgCO3(s)  →  (CH3COO)2Mg(aq) + CO2(g) + H2O(l) (A) 44% (B) 58% (C) 88% (D) 100%
    Chemical synthesis
17. Q17 · 2021 QCAA · Paper 1 · 1 mark
    QUESTION 17 Determine the concentration of hydrogen ions (H+) in an aqueous solution containing 1.2 × 10–3 M hydroxide ions (OH–). (A) 1.2 × 1011 (B) 8.3 × 10–12 (C) 8.3 × 10–17 (D) 1.2 × 10–17
    Acids, bases and titration
18. Q18 · 2021 QCAA · Paper 1 · 1 mark
    QUESTION 18 Identify the major product when 2-methylbut-2-ene reacts with water under acidic conditions. (A) (CH3)2CHCOCH3 (B) (CH3)2C(OH)CH2CH3 (C) (CH3)2CHCH(OH)CH3 (D) (CH3)2C(OH)CH(OH)CH3
    Organic chemistry
19. Q19 · 2021 QCAA · Paper 1 · 1 mark
    QUESTION 19 To form ethanol biofuel in the fermentation of glucose, a catalyst is used because (A) less energy is required and the rate of reaction is increased. (B) less energy is required and the rate of reaction is decreased. (C) more energy is required and the rate of reaction is increased. (D) more energy is required and the rate of reaction is decr…
    Chemical equilibrium
20. Q20 · 2021 QCAA · Paper 1 · 1 mark
    QUESTION 20 Identify the ester linkage in aspartame. (A) O O CH3 O NH OH NH2 O (B) O O CH3 O NH O OH NH2 (C) O O CH3 O NH OH NH2 O (D) O O O CH3 NH OH NH2 O
    Organic chemistry
21. Q21 · 2021 QCAA · Paper 1 · 3 marks
    QUESTION 21  (3 marks) Calculate the pH of a 0.1 M aqueous solution of Ba(OH)2, assuming complete dissociation. Show your working. pH = (to one decimal place)
    Acids, bases and titration
22. Q22 · 2021 QCAA · Paper 1 · 4 marks
    QUESTION 22  (4 marks) The structural formula for pentane (C5H12) is shown. H H H H H H C C C C C H H H H H H Draw the structural formulas for two structural isomers of pentane. Name each isomer. a) Isomer 1 [2 marks] Note: If you make a mistake in the drawing, cancel it by ruling a single diagonal line through your work and use the additional response spac…
    Organic chemistry
23. Q23 · 2021 QCAA · Paper 1 · 5 marks
    QUESTION 23  (5 marks) Aspartame is a methyl ester of a dipeptide that hydrolyses to form methanol and two amino acids. The structure of aspartame is shown. O O OCH3 NH OH NH2 O a) Identify the two amino acids that form aspartame. [1 mark] A hydrolysed sample of aspartame was analysed with silica thin layer chromatography (TLC), using a mixture of butanol a…
    Polymers and biomolecules
24. Q24 · 2021 QCAA · Paper 1 · 6 marks
    QUESTION 24  (6 marks) The cell diagram represents a voltaic cell at standard conditions. The copper solution is blue because of the presence of Cu2+(aq) ions. The acidified permanganate solution is purple because of the presence of MnO4 –(aq) ions. Half-cell Half-cell Cu(s) Cu2+(aq) MnO 4–(aq) Pt(s) Salt bridge a) Predict which direction the electrons will…
    Redox and electrochemistry