This check needs JavaScript to record answers. The reviewed questions are listed below for study.
What does polyunsaturated mean when describing a food oil molecule?
- It contains more than one carbon-carbon double bond in its hydrocarbon chains.
- It contains many separate water molecules.
- Every carbon-carbon bond is single but the oil contains many molecules.
- It contains one double bond in the entire food sample.
Which condensed formula represents butanoic acid?
- CH₃CH₂CH₂CO₂H
- CH₃CH₂CO₂H
- CH₃CH₂CH₂CH₂OH
- CH₃CH₂CH=CH₂
Which linkage and use pairing is correct for Terylene?
- Ester linkage, –COO–; used in materials such as clothing or curtains
- Only C–C links from ethene; used only as a gas
- Amide linkage, –CONH–; identified as nylon
- Glycosidic linkage; used as starch in food
Waste poly(ethene) is chemically recycled by cracking. What is the intended outcome?
- Smaller hydrocarbons that can be used as fuels or chemical feedstocks
- A single polymer chain longer than the original waste.
- Only elemental sodium and chlorine.
- Unchanged plastic pieces with only a new colour.
Which molecular formula and name are correctly paired for an unbranched alkene with one C=C bond?
- C₃H₆ — propene
- C₃H₈ — propene
- C₂H₆ — ethene
- C₂H₄ — propene
Which disposal method is most consistent with reducing landfill when plastics are suitable for reprocessing?
- Landfill
- Recycling
- Dumping in the ocean
- Leaving as litter
Which statement about bioethanol is appropriately cautious?
- It is non-renewable because every fuel must come from crude oil
- It is renewable, but farming, processing and transport can add life-cycle emissions
- It is automatically carbon neutral under all production methods
- It cannot release carbon dioxide when burned
What chemical change helps convert liquid unsaturated vegetable oil into more solid margarine?
- Hydrogen adds across some C=C bonds, decreasing unsaturation and increasing the melting range.
- Oxygen removes every carbon atom from the oil.
- Water hydrolyses all molecules into methane gas.
- Hydrogen creates extra C=C bonds and increases unsaturation.
Why is thin poly(ethene) useful as clingfilm but unsuitable for direct contact with a very hot heating element?
- It forms flexible, water-resistant films but softens or melts when heated strongly.
- It is useful only because it is a giant ionic lattice.
- It becomes stronger without limit as temperature rises.
- It reacts explosively with all food at room temperature.
Ethanol is warmed with a small amount of acidified potassium manganate(VII), which is completely consumed. Which observation accompanies this oxidation?
- A colourless solution turns purple
- The purple colour becomes more intense
- The purple solution is decolourised
- A white precipitate forms immediately
Which has the higher boiling point: butane or methylpropane?
- Butane
- Methylpropane
- Same boiling point
- Cannot be compared
What happens in mechanical recycling of a thermoplastic?
- It is sorted, cleaned and remelted without deliberately breaking every polymer chain
- It is completely hydrolysed back to its monomers
- It is burned to carbon dioxide and called the same polymer
- Every covalent bond is deliberately broken to recover isolated atoms
Why are condensation polymers often more susceptible to chemical hydrolysis than addition polymers?
- Because condensation polymers always dissolve in water
- Because condensation polymers contain linkages (e.g. ester/amide) that can be broken by hydrolysis
- Because addition polymers contain $\ce{C=C}$ bonds in the polymer chain
- Because addition polymers always contain chlorine
Why can careless disposal of non-biodegradable plastic cause long-term pollution?
- It persists, accumulates in habitats and can fragment into smaller pieces without truly biodegrading.
- It disappears immediately because non-biodegradable means water-soluble.
- It always changes completely into harmless oxygen in sunlight.
- It can affect only factories and never ecosystems.
Which prefix corresponds to 3 carbon atoms?
What is a monomer?
- A small molecule that joins to form a polymer
- A large molecule that cannot react
- A catalyst used in cracking
- A product of combustion
Which pair correctly matches a functional group to its homologous series?
- $\ce{-OH}$ → alkanes
- $\ce{C=C}$ → alkenes
- $\ce{-COOH}$ → alcohols
- $\ce{-COO-}$ → alkanes
Which is the molecular formula of ethanol?
- $\ce{CH3OH}$
- $\ce{C2H5OH}$
- $\ce{C2H4}$
- $\ce{C2H6}$
Which statement is most correct about alkanes as fuels?
- They release energy on combustion, so they are useful fuels
- They do not burn in oxygen
- They produce only water when burned
- They are non-flammable
Which statement about addition polymers is most correct at O-Level?
- They are formed from monomers containing $\ce{C=C}$ bonds and no small molecule is produced
- They are formed from alcohol and carboxylic acid monomers and always produce water
- They contain ionic bonds
- They are always biodegradable
Which equation shows esterification of methanol with methanoic acid?
- $\ce{CH3OH + HCOOH -> HCOOCH3 + H2O}$
- $\ce{CH3OH + HCOOH -> CH3COOCH3 + H2O}$
- $\ce{CH3OH + HCOOH -> HCOOCH3 + H2}$
- $\ce{CH3OH + HCOOH -> CH4 + CO2}$
Which statement is most correct about the term “hydrocarbon”?
- A compound containing carbon, hydrogen and oxygen
- A compound containing only carbon and hydrogen
- Any compound containing carbon
- Any compound containing hydrogen
Which statement about cracking is correct?
- Cracking is a physical separation of fractions by boiling point
- Cracking breaks large hydrocarbons into smaller alkanes and alkenes
- Cracking only produces carbon dioxide and water
- Cracking turns alkenes into alkanes by addition of hydrogen
Under matching conditions, equal moles of molecules from oils P and Q react completely with bromine. P consumes more bromine than Q. What inference about the oils is supported?
- P has a greater average number of carbon-carbon double bonds per molecule and is more unsaturated.
- P is more saturated because bromine removes double bonds before measurement.
- Q must contain no carbon atoms.
- Bromine consumption measures only molecular mass and never bonding.
Which ion is produced when ethanoic acid ionises in water?
- $\ce{OH-}$
- $\ce{H+}$
- $\ce{Na+}$
- $\ce{Cl-}$
Which statement about fractions at the top of the column is correct?
- They have larger molecules and higher boiling points
- They have smaller molecules and lower boiling points
- They are more viscous and less flammable
- They are solids at room temperature
Which statement correctly describes hydration of ethene?
- Ethanol reacts with steam to form ethene
- Ethene reacts with steam to form ethanol
- Ethene reacts with oxygen to form ethanol
- Glucose reacts with steam to form ethanol
Which set of observations supports classifying compounds as one homologous series?
- They share a general formula and characteristic structural features, react similarly, and show gradual physical-property changes with molecular size.
- They have identical molecular formulae but unrelated reactions.
- They contain the same total number of atoms and have identical boiling points.
- They share only a colour, while their functional groups and formula patterns differ.
Which statement best describes a homologous series?
- A group of compounds with different functional groups
- A group with a general formula, similar chemical properties and a gradation in physical properties as molecular size increases
- A group of compounds with the same number of carbon atoms
- A group of compounds that are all isomers
As hydrocarbons in crude oil get larger (more carbon atoms), which property generally increases?
- Volatility
- Boiling point
- Flammability
- Ease of ignition
As you move from bottom to top of the column, viscosity generally:
- Increases
- Decreases
- Stays constant
- Becomes infinite
Which pair are successive members of the same homologous series?
- $\ce{C2H6}$ and $\ce{C3H8}$
- $\ce{C2H6}$ and $\ce{C2H4}$
- $\ce{C3H8}$ and $\ce{C3H6}$
- $\ce{CO2}$ and $\ce{CH4}$
What are the products of glucose fermentation by yeast?
- Methane and chlorine
- Ethanol and oxygen
- Ethanol and carbon dioxide
- Ethanoic acid and oxygen
In fermentation, glucose is converted into:
- Ethanol and oxygen
- Ethanol and carbon dioxide
- Ethene and steam
- Ethanoic acid and hydrogen
Which test confirms carbon dioxide produced during fermentation?
- A lighted splint gives a squeaky pop
- Turns limewater milky
- Glowing splint relights
- Damp red litmus turns blue
Bioethanol is commonly produced from glucose by:
- Neutralisation
- Electrolysis
- Fermentation using yeast
- Thermal decomposition
Why can crude oil be separated by fractional distillation?
- Its hydrocarbons have different boiling ranges
- Each fraction has a different proton number for carbon
- Crude oil is one compound that decomposes into elements
- Its hydrocarbons all boil at exactly the same temperature