Question 1:

The condensed formula is C₂H₅OH (or CH₃CH₂OH).
This shows you how the atoms are grouped:

• CH₃– = a carbon atom bonded to three hydrogens (a methyl group).

• –CH₂– = a carbon atom bonded to two hydrogens.

• –OH = an oxygen atom single-bonded to a hydrogen atom. This is the hydroxyl functional group, which is what makes ethanol an alcohol.

  This description matches diagram C.

*These A.I. responses have been individually checked to ensure they match the accepted answer, but explanations may still be incorrect. Responses may give guidance but the A.I. might not be able to answer the question! This is particularly the case for questions based on diagrams, which the A.I. typically cannot interpret.
Grade Gorilla uses Gemini, Deepseek and a range of other A.I. chatbots to generate the saved responses. Some answers have had human intervention for clarity or where the A.I. has not been able to answer the question.

Question 2:

The correct answer is C. Fractional distillation / cracking.

Explanation:

• Process 1 (Crude Oil → Long Chain Fractions):
  Crude oil is a mixture of different hydrocarbons with different boiling points. It is separated into fractions (like petrol, kerosene, diesel, etc.) by fractional distillation in a fractionating column. This is a physical separation process.

• Process 2 (Long Chain Fractions → Ethene):
  Long-chain hydrocarbon fractions are broken down into smaller, more useful molecules (like ethene) by a chemical process called cracking. This involves heating the long-chain alkanes to a high temperature (around 500–600°C), often with a catalyst (like alumina or silica), to break the large molecules into smaller alkenes and alkanes.

Why the other options are wrong:

• Fermentation (Options B and D) is a biological process used to produce ethanol from sugars (using yeast), not to obtain ethene from crude oil fractions.

• Polymerisation (Options A and B) is the process of joining many small alkene molecules (like ethene) together to form long-chain polymers (like polyethene). This is the opposite of cracking and is not used to produce ethene from crude oil fractions.

So, the correct pairing is Fractional distillation for process 1 and Cracking for process 2.

*These A.I. responses have been individually checked to ensure they match the accepted answer, but explanations may still be incorrect. Responses may give guidance but the A.I. might not be able to answer the question! This is particularly the case for questions based on diagrams, which the A.I. typically cannot interpret.
Grade Gorilla uses Gemini, Deepseek and a range of other A.I. chatbots to generate the saved responses. Some answers have had human intervention for clarity or where the A.I. has not been able to answer the question.

Question 3:

The correct answer is addition (specifically, hydration or electrophilic addition).

Explanation:
In this reaction, ethene (C₂H₄) reacts with steam (H₂O) to produce ethanol (C₂H₅OH).

• Ethene is an alkene, which contains a carbon-carbon double bond.

• During the reaction, the double bond breaks open, and the H and OH from the water molecule add directly across the two carbon atoms.

Because the atoms from the water molecule are added to the unsaturated alkene, and nothing is removed, this is classified as an addition reaction. Specifically, because water (steam) is being added, it is also called a hydration reaction.

The equation for reference:
C₂H₄ + H₂O → C₂H₅OH

*These A.I. responses have been individually checked to ensure they match the accepted answer, but explanations may still be incorrect. Responses may give guidance but the A.I. might not be able to answer the question! This is particularly the case for questions based on diagrams, which the A.I. typically cannot interpret.
Grade Gorilla uses Gemini, Deepseek and a range of other A.I. chatbots to generate the saved responses. Some answers have had human intervention for clarity or where the A.I. has not been able to answer the question.

Question 4:

The correct answer is A. yeast / 30°C.

Explanation:
Fermentation is a biological process where enzymes in yeast break down glucose (sugar) into ethanol and carbon dioxide.

• Substance added: The microorganism yeast must be added because it contains the necessary enzymes (zymase) to catalyze the reaction.

• Temperature: The ideal temperature for this reaction is around 30°C (room temperature to slightly warm). This is warm enough for the enzymes to work efficiently, but not so hot that they become denatured (destroyed).

Why the other options are wrong:

• Option B (acid catalyst / 100°C): An acid catalyst at 100°C is used for the hydration of ethene to produce ethanol (the industrial method), not for fermentation of sugars.

• Option C (yeast / 100°C): At 100°C, the yeast and its enzymes would be completely denatured (killed) by the boiling temperature, so no fermentation would occur.

• Option D (acid catalyst / 30°C): An acid catalyst is not used in fermentation; this process relies on living biological organisms (yeast), not chemical catalysts.

*These A.I. responses have been individually checked to ensure they match the accepted answer, but explanations may still be incorrect. Responses may give guidance but the A.I. might not be able to answer the question! This is particularly the case for questions based on diagrams, which the A.I. typically cannot interpret.
Grade Gorilla uses Gemini, Deepseek and a range of other A.I. chatbots to generate the saved responses. Some answers have had human intervention for clarity or where the A.I. has not been able to answer the question.

Question 5:

The correct answer is B. turns limewater milky.

Explanation:
The fermentation of glucose produces ethanol and carbon dioxide (CO₂) as the other product.

The balanced equation is:
C₆H₁₂O₆ → 2C₂H₅OH + 2CO₂

Carbon dioxide is the gas produced. The classic chemical test for carbon dioxide is to bubble it through limewater (calcium hydroxide solution). If CO₂ is present, the limewater turns from clear and colourless to cloudy/milky due to the formation of insoluble calcium carbonate.

Why the other options are wrong:

• A (pops with a lighted splint): This is the test for hydrogen gas, not carbon dioxide.

• C (relights a glowing splint): This is the test for oxygen gas.

• D (turns damp UI paper blue): This is a test for an alkali (like ammonia gas), not carbon dioxide. (CO₂ is slightly acidic and would turn damp blue litmus paper red.)

*These A.I. responses have been individually checked to ensure they match the accepted answer, but explanations may still be incorrect. Responses may give guidance but the A.I. might not be able to answer the question! This is particularly the case for questions based on diagrams, which the A.I. typically cannot interpret.
Grade Gorilla uses Gemini, Deepseek and a range of other A.I. chatbots to generate the saved responses. Some answers have had human intervention for clarity or where the A.I. has not been able to answer the question.

Question 6:

The correct answer is D. fractional distillation.

Explanation:
After fermentation, the reaction mixture contains ethanol, water, and other impurities. To obtain a concentrated (or pure) solution of ethanol from this mixture, you need to separate the ethanol from the water.

• Fractional distillation is used because ethanol and water have different boiling points (ethanol boils at 78°C, water at 100°C). By heating the mixture, the ethanol evaporates first, rises up the fractionating column, condenses, and is collected separately, leaving much of the water behind. This process can produce a concentrated ethanol solution (up to about 96% pure).

Why the other options are wrong:

• A (evaporation): This would just boil away all the liquid, leaving any dissolved solids behind. You wouldn't be able to collect a concentrated liquid ethanol solution this way.

• B (filtration): This is used to separate an insoluble solid from a liquid (e.g., removing yeast cells from the fermentation mixture). Ethanol and water are both liquids, so filtration won't separate them.

• C (chromatography): This is used to separate and identify different dissolved substances in small amounts (e.g., inks or dyes), not to concentrate a liquid on a large scale.

*These A.I. responses have been individually checked to ensure they match the accepted answer, but explanations may still be incorrect. Responses may give guidance but the A.I. might not be able to answer the question! This is particularly the case for questions based on diagrams, which the A.I. typically cannot interpret.
Grade Gorilla uses Gemini, Deepseek and a range of other A.I. chatbots to generate the saved responses. Some answers have had human intervention for clarity or where the A.I. has not been able to answer the question.

Question 7:

The correct answer is B. C₂H₅OH + 3O₂ → 2CO₂ + 3H₂O

Explanation:
Complete combustion of a hydrocarbon (or an alcohol like ethanol) requires enough oxygen so that the only products are carbon dioxide (CO₂) and water (H₂O).

Let's check the atom balance for Option B:

• Left side: 2 carbons (C₂), 6 hydrogens (H₅ + H from OH = 6), and 7 oxygens (1 from ethanol + 6 from 3O₂ = 7).

• Right side: 2 carbons (from 2CO₂), 6 hydrogens (from 3H₂O), and 7 oxygens (4 from 2CO₂ + 3 from 3H₂O = 7).

The equation is perfectly balanced.

Why the other options are wrong:

• A (2C₂H₅OH + 3O₂ → 4CO₂ + 6H₂): This shows hydrogen gas (H₂) as a product instead of water. In complete combustion, hydrogen always forms water (H₂O). Also, hydrogen gas is highly flammable, so this would not be complete combustion.

• C (2C₂H₅OH + O₂ → 4CO + 6H₂): This shows carbon monoxide (CO) and hydrogen gas (H₂) as products. Carbon monoxide is produced during incomplete combustion (when there is insufficient oxygen), not complete combustion.

• D (C₂H₅OH + 2O₂ → 2CO + 3H₂O): This also shows carbon monoxide (CO) instead of carbon dioxide (CO₂), indicating incomplete combustion. Additionally, the oxygen atoms don't balance correctly (3 on the left, 5 on the right).

*These A.I. responses have been individually checked to ensure they match the accepted answer, but explanations may still be incorrect. Responses may give guidance but the A.I. might not be able to answer the question! This is particularly the case for questions based on diagrams, which the A.I. typically cannot interpret.
Grade Gorilla uses Gemini, Deepseek and a range of other A.I. chatbots to generate the saved responses. Some answers have had human intervention for clarity or where the A.I. has not been able to answer the question.

Question 8:

The correct answer is A. solvent.

Explanation:
Ethanol is a very versatile solvent—it dissolves a wide range of substances that water cannot dissolve on its own (such as many organic compounds, oils, fats, and resins).

You will commonly find ethanol used as a solvent in:

• Perfumes and aftershaves (dissolving fragrance oils)

• Tinctures (like iodine tincture for antiseptics)

• Cleaning products and hand sanitizers

• Paints, varnishes, and inks

Why the other options are wrong:

• B (monomer): A monomer is a small molecule that joins together to form a polymer (e.g., ethene is the monomer for polyethene). Ethanol is not used as a monomer in polymerization reactions.

• C (glue): While ethanol can be an ingredient in some glue formulations (as a solvent), it is not itself a glue—it does not have adhesive properties.

• D (flavouring): Ethanol is used as a carrier for flavourings (e.g., in vanilla extract) and is the alcohol in alcoholic beverages, but it is not typically classified as a flavouring agent itself. It has a distinct taste/smell but is not added specifically for flavour in the way a spice or essence is.

*These A.I. responses have been individually checked to ensure they match the accepted answer, but explanations may still be incorrect. Responses may give guidance but the A.I. might not be able to answer the question! This is particularly the case for questions based on diagrams, which the A.I. typically cannot interpret.
Grade Gorilla uses Gemini, Deepseek and a range of other A.I. chatbots to generate the saved responses. Some answers have had human intervention for clarity or where the A.I. has not been able to answer the question.

Question 9:

The correct answer is B. two functional groups.

Explanation:
For a condensation polymer to form, each monomer must have at least two functional groups (e.g., -OH, -COOH, -NH₂). This allows the monomers to react together in a chain, forming new bonds and releasing a small molecule (like water or HCl) as a by-product with each new bond formed.

• Example: In the formation of nylon or polyester, each monomer has two reactive groups (a diacid and a diamine, or a diacid and a diol). This two-sided reactivity allows the chain to grow in both directions, creating a long polymer.

Why the other options are wrong:

• A (a double C=C bond): This is a requirement for addition polymers (like polyethene from ethene), not condensation polymers. Condensation polymers do not require a C=C bond in the monomer.

• C (oxygen atoms): While many condensation polymers (like polyesters) do contain oxygen, it is not a strict requirement. For example, nylon contains nitrogen but no oxygen in its monomer structure. Oxygen is not mandatory.

• D (at least four carbon atoms): There is no minimum carbon requirement. For example, the condensation polymer polyglycolic acid is made from a monomer with only 2 carbon atoms.

*These A.I. responses have been individually checked to ensure they match the accepted answer, but explanations may still be incorrect. Responses may give guidance but the A.I. might not be able to answer the question! This is particularly the case for questions based on diagrams, which the A.I. typically cannot interpret.
Grade Gorilla uses Gemini, Deepseek and a range of other A.I. chatbots to generate the saved responses. Some answers have had human intervention for clarity or where the A.I. has not been able to answer the question.

Question 10:

The correct answer is C. addition / condensation.

Explanation:

• Polythene (polyethylene) is an addition polymer. It is made from ethene (C₂H₄) monomers, which contain a C=C double bond. During polymerization, the double bond breaks and the monomers simply join together end-to-end. No small molecules (like water) are lost in the process.

• Nylon is a condensation polymer. It is made from monomers containing two functional groups (e.g., a dicarboxylic acid and a diamine). When these monomers join, they form amide linkages and release a small molecule (such as water or HCl) as a by-product with each new bond.

Summary of why the other options are wrong:

• A (condensation / condensation): Incorrect because polythene is not a condensation polymer.

• B (condensation / addition): Incorrect because polythene is not condensation, and nylon is not addition.

• D (addition / addition): Incorrect because nylon is not an addition polymer; it requires monomers with two functional groups and releases a by-product.

*These A.I. responses have been individually checked to ensure they match the accepted answer, but explanations may still be incorrect. Responses may give guidance but the A.I. might not be able to answer the question! This is particularly the case for questions based on diagrams, which the A.I. typically cannot interpret.
Grade Gorilla uses Gemini, Deepseek and a range of other A.I. chatbots to generate the saved responses. Some answers have had human intervention for clarity or where the A.I. has not been able to answer the question.