Organic chemistry — IGCSE Sciences - Co-Ordinated (0973) questions by topic
Organic chemistry questions identify an unsaturated hydrocarbon from a compound table, pick correct cracking equations for long alkane chains, state properties of alkanes, and recognise the structure of nylon among displayed candidates, worth from 1 to 12 marks.
State, identify and describe top the command words in this IGCSE Co-ordinated Sciences topic, with complete and explain also common: identify a structure by counting bonds and atoms precisely, not by appearance alone. 40 real questions from 2023 to 2025 papers are gathered here. Submit each attempt for instant marking so a cracking equation with unbalanced atoms is caught immediately.
May–June 2025, Paper 11
Which compound is an alkene? Four displayed (structural) formulae are shown. A shows ethane, with two carbon atoms joined by a single C–C bond and each carbon bonded to hydrogen…
Answer this question and get it marked →Which statement describes poly(ethene)? A It is formed from monomer molecules which each contain two atoms. B It is formed from a saturated hydrocarbon monomer. C It is formed in…
Answer this question and get it marked →Naphtha is obtained from petroleum. What is a use for naphtha? A cooking B heating C making roads D making chemicals
Answer this question and get it marked →May–June 2025, Paper 12
Which property allows petroleum to be separated by fractional distillation? A boiling point B colour C density D melting point
Answer this question and get it marked →Which compound is the main constituent of natural gas? The four options show displayed (structural) formulae: A a straight chain of four carbon atoms each bonded to hydrogen…
Answer this question and get it marked →Which statement about alkanes is correct? A They contain one double covalent bond. B They contain only single covalent bonds. C They form polymers. D They react with aqueous…
Answer this question and get it marked →May–June 2025, Paper 21
The structure of compound P is shown. It is a chain of four carbon atoms, each fully bonded to hydrogen atoms, with the end carbon bonded to an -O-H (hydroxyl) group:…
Answer this question and get it marked →May–June 2025, Paper 22
A molecule of methane contains one carbon atom and has the formula CH₄. A molecule of octane contains eight carbon atoms. How many hydrogen atoms are in a molecule of octane? A 11…
Answer this question and get it marked →Large alkane molecules are cracked to form smaller molecules. Which equations represent cracking reactions? 1 C₁₈H₃₈ → 2C₆H₁₄ + C₆H₁₂ 2 C₁₈H₃₈ → H₂ + 3C₆H₁₂ 3 C₁₅H₃₂ → C₅H₁₀ +…
Answer this question and get it marked →Which diagram represents the structure of nylon? Four candidate displayed structures are shown: A a saturated hydrocarbon chain (four CH₂-type carbons each with H atoms, no other…
Answer this question and get it marked →May–June 2025, Paper 31
Natural gas and petroleum are two fossil fuels. State the name of one other fossil fuel.
Answer this question and get it marked →May–June 2025, Paper 32
Ethanol has the formula C2H5OH. Explain why ethanol is not a hydrocarbon.
Answer this question and get it marked →May–June 2025, Paper 41
Petroleum is separated into useful fractions by fractional distillation. Fig. 8.1 shows the fractions obtained from a fractionating column, with petroleum fed in near the bottom.…
Answer this question and get it marked →May–June 2025, Paper 42
Fig. 6.1 shows the structural formula of a molecule, X. The structure is a chain: H2N-CH2-CH2-CH2-CH2-CH2-CH2-NH2, i.e. an amine group (NH2) at each end joined by a chain of six…
Answer this question and get it marked →May–June 2024, Paper 11
Which molecule reacts with aqueous bromine? [Structures A-D: A = methane, B = propene (contains a C=C double bond), C = ethane, D = propane.] A molecule A B molecule B C molecule…
Answer this question and get it marked →May–June 2024, Paper 12
Poly(ethene) is made from ethene by addition polymerisation. Which word describes ethene in this process? A fuel B catalyst C monomer D solvent
Answer this question and get it marked →May–June 2024, Paper 21
The structure of a molecule of compound X is shown (ethene, C2H4, with a C=C double bond). [Structure: ethene C2H4.] Which two formulas represent compounds that are in the same…
Answer this question and get it marked →Which molecules can be used as monomers in polymerisation processes? [Structures: 1 = chloroethene (an alkene, addition monomer), 2 = an alcohol, 3 = an amino acid (condensation…
Answer this question and get it marked →May–June 2024, Paper 22
A gasoline fraction from the fractional distillation of petroleum includes compounds with the formulas C6H14 and C12H26. Which statements about these compounds are correct? 1…
Answer this question and get it marked →The molecule shown contains some amide linkages (-N(H)-C(=O)-). How many amide linkages are present in this molecule? [Diagram: a polypeptide chain with amide (peptide) linkages…
Answer this question and get it marked →May–June 2024, Paper 31
Petroleum is separated into different fractions. Table 8.1 shows the percentage composition of a 500 kg sample of petroleum: fraction X 10%, gasoline (petrol) 30%, naphtha 30%,…
Answer this question and get it marked →May–June 2024, Paper 32
Ethanol has the formula C2H5OH. Complete Fig. 5.1 to show the structure of an ethanol molecule.
Answer this question and get it marked →May–June 2024, Paper 42
Fig. 8.1 shows the structures of three carbon compounds (ethene, ethanoic acid, ethanol). Ethene is an unsaturated hydrocarbon. Explain how the structure of ethene shows that…
Answer this question and get it marked →October–November 2024, Paper 31
Fig. 11.1 shows the structural formula of an ethene molecule. [Fig. 11.1: Structural formula of ethene showing H₂C=CH₂ with all H atoms shown.] State the total number of atoms in…
Answer this question and get it marked →May–June 2023, Paper 11
Petroleum is separated into fractions by fractional distillation. Information about uses of some fractions and positions in the fractionating column is shown. 1 gasoline: making…
Answer this question and get it marked →Which process forms ethanol? A combustion B cracking C distillation D fermentation
Answer this question and get it marked →May–June 2023, Paper 12
Naphtha is obtained by the fractional distillation of petroleum. Which statements about naphtha are correct? 1 It burns to form carbon dioxide and water. 2 It is a mixture of…
Answer this question and get it marked →Which diagram represents a molecule that is formed by fermentation? [Diagrams A-D: A = methane CH4, B = ethane C2H6, C = ethene C2H4, D = ethanol C2H5OH.] A diagram A B diagram B…
Answer this question and get it marked →May–June 2023, Paper 21
Petroleum is separated into fractions by fractional distillation. Information about uses of some fractions and positions in the fractionating column is shown. 1 gasoline: making…
Answer this question and get it marked →Which structure represents the addition polymer made from the monomer propene, C3H6? [Structures A-D: repeat units with CH3 and H groups on the carbon chain; A is the correct…
Answer this question and get it marked →May–June 2023, Paper 22
Naphtha is obtained by the fractional distillation of petroleum. Which statements about naphtha are correct? 1 It burns to form carbon dioxide and water. 2 It is a mixture of…
Answer this question and get it marked →The structure of an addition polymer is shown: a repeat unit with H and CH3 groups on adjacent carbons, repeated n times (poly(propene)). [Structure: -CH(H)CH(CH3)- repeat unit;…
Answer this question and get it marked →May–June 2023, Paper 32
Fig. 8.1 shows the separation of petroleum into useful fractions (only refinery gas at 50 C and diesel oil at 400 C shown). Petroleum is a fossil fuel. State the name of one other…
Answer this question and get it marked →May–June 2023, Paper 41
Look at the structures of the carbon compounds shown in Fig. 11.1 (A = ethene C2H4; B = ethanol C2H5OH; C = ethane C2H6; D = ethane-like structure; E = ethene repeat unit /…
Answer this question and get it marked →May–June 2023, Paper 42
Alkanes are saturated hydrocarbons. State what is meant by the term saturated hydrocarbon.
Answer this question and get it marked →October–November 2023, Paper 11
Which statement about petroleum is correct? A It contains mostly alkene molecules. B It is a mixture of hydrocarbons. C It is separated into fractions by cracking. D Its main…
Answer this question and get it marked →Which statement about poly(ethene) is correct? A It always contains less than 12 carbon atoms. B It is formed from ethane. C It is formed from ethene. D It occurs naturally.
Answer this question and get it marked →October–November 2023, Paper 21
Which statements about monomers and polymers are correct? 1 Different polymers can have different linkages between monomers. 2 An addition polymerisation reaction produces more…
Answer this question and get it marked →October–November 2023, Paper 31
Table 5.1 shows five compounds and their formulae: A = CO, B = CO2, C = CH4, D = C2H4, E = C2H6. State the compound from Table 5.1 that is an unsaturated hydrocarbon.
Answer this question and get it marked →October–November 2023, Paper 41
Crude oil contains hydrocarbon molecules. State what is meant by a hydrocarbon.
Answer this question and get it marked →Other IGCSE Sciences - Co-Ordinated topics
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- Electricity and magnetism (65)
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- Chemical reactions (22)
- The Periodic Table (22)
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