Question 1:

The correct answer is C. sunlight or u.v. light.

Explanation:
Ethane reacts with bromine via a free-radical substitution mechanism. This reaction requires energy to break the bromine-bromine bond homolytically to form bromine radicals. The most common way to initiate this is by providing ultraviolet (u.v.) light or sunlight.

• Option A (300°C) is a temperature used for cracking hydrocarbons, not for the bromination of alkanes.

• Option B (alumina or silica) are catalysts used in cracking or dehydration reactions, not in halogenation.

• Option D (60 atm) is a high pressure used in polymerization or other industrial processes, not for this reaction.

*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 A. C₂H₆ + Br₂ → C₂H₅Br + HBr

Explanation:
The reaction between ethane and bromine under u.v. light is a substitution reaction. One hydrogen atom in the ethane molecule is replaced by a bromine atom, forming bromoethane (C₂H₅Br) and hydrogen bromide (HBr) as a byproduct.

• Option B is incorrect because this would be an elimination/dehydrogenation reaction (and would require different conditions), not a substitution. Also, it incorrectly shows two bromines adding to the same carbon.

• Option C is incorrect because it suggests an addition reaction where both bromine atoms add to the molecule, which is not how alkanes react. It also incorrectly gives the formula C₂H₆Br₂ (which should be C₂H₄Br₂ for a dibromo compound).

• Option D is incorrect because it shows the reaction of ethene (C₂H₄), not ethane (C₂H₆). This equation is for the addition of bromine to an alkene, not the substitution reaction of an alkane.

*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 substitution (specifically, a free-radical substitution reaction).

Explanation:
In this reaction, a bromine atom replaces (substitutes) one of the hydrogen atoms on the ethane molecule. The original C-H bond is broken, and a new C-Br bond is formed, while the displaced hydrogen pairs with the other bromine atom to form HBr.

Because it involves alkanes (which are saturated hydrocarbons) and takes place via a chain mechanism involving bromine radicals, it is more precisely called a free-radical substitution reaction.

*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 B. same molecular formula but a different structural formula.

Explanation:
Isomers are compounds that have the same number and type of atoms (i.e., the same molecular formula) but are arranged differently in space or have different connectivity between those atoms (i.e., a different structural formula).

• Option A is incorrect because having the same general formula but different structural formulas describes a homologous series (e.g., all alkanes have the general formula CₙH₂ₙ₊₂), not isomers.

• Option C is incorrect because if the molecular formula is different, they are completely different compounds, not isomers.

• Option D is incorrect because isomers can have the same functional group (e.g., chain isomers) or different functional groups (e.g., functional group isomers). Having a different functional group is one type of isomerism, but it is not the defining definition of all isomers. The core definition is simply the same molecular formula but a different structural arrangement.

*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:

Understanding Isomers

Isomers are molecules that have the same molecular formula (the same number of each type of atom) but a different structural arrangement.

Hexane's Formula: Hexane is an alkane with 6 carbon atoms and 14 hydrogen atoms

Option A has a double bond and only 12 hydrogen atom, so is not an isomer of hexane.

Option B and C are just Hexane:

If you trace the carbon line from the bottom-left branch, through the middle four carbons, and up to the top-right branch, it forms one single, continuous, unbranched chain of 6 carbons. C does the same thing in an L-shape. Because they are unbranched, B and C are just hexane drawn in a bent shape, not isomers.

Option D is a true Isomer:

It consists of a 4-carbon main chain (butane) with two methyl branches -CH₃ attached to the middle carbons. This molecule is 2,3-dimethylbutane.Since it has the same molecular formula C₆H₁₄ but a completely different branched structure, D is the correct structural isomer.

*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:

To determine which structures are isomers of C₄H₈ we must count the carbon (C) and hydrogen (H) atoms in each structure.

Isomers share the same molecular formula but have different arrangements.

Breakdown of Structures

Conclusion

• X is an alkene (straight chain with a double bond).
• Y is an alkane (saturated chain), so it has too many hydrogens.
• Z is a cycloalkane (ring structure).

Both X and Z have the molecular formula C₄H₈. Therefore, the correct answer is C (X and Z only).

*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:

First, let's identify the molecular formula for each compound:

P: C₄H₁₀ (Butane)

Q: C₄H₈ (But-1-ene)

R: C₃H₈ (Propane)

S: C₄H₈ (But-2-ene)

Which compounds are isomers?

Isomers are molecules that have the same molecular formula but different structural arrangements.Q and S both have the formula C₄H₈.

Answer: D. Q and S

*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:

First, let's identify the molecular formula for each compound:

P: C₄H₁₀ (Butane)

Q: C₄H₈ (But-1-ene)

R: C₃H₈ (Propane)

S: C₄H₈ (But-2-ene)

Which compound(s) will decolourise bromine water immediately?

Bromine water is a test for unsaturation (double or triple bonds). Compounds with C=C double bonds (alkenes) react quickly with bromine water, changing it from orange/brown to colorless.

Q and S are both alkenes containing a double bond.

Answer: D. Q and S

*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:

First, let's identify the molecular formula for each compound:

P: C₄H₁₀ (Butane)

Q: C₄H₈ (But-1-ene)

R: C₃H₈ (Propane)

S: C₄H₈ (But-2-ene)

Addition polymerization requires unsaturated monomers that contain at least one carbon-carbon double bond C=C.

Q and S are alkenes containing double bonds, which can open up to link together into long polymer chains.

Correct Answer: D (Q and S)

*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:

First, let's identify the molecular formula for each compound:

P: C₄H₁₀ (Butane)

Q: C₄H₈ (But-1-ene)

R: C₃H₈ (Propane)

S: C₄H₈ (But-2-ene)

A homologous series is a family of organic compounds that share the same general formula, functional group, and similar chemical properties, with each consecutive member differing by a -CH₂ unit.

P (Butane), C₄H₁₀ and R (Propane, C₃H₈) are both alkanes sharing the general formula C_nH_2n+2.

Correct Answer: B (P and R)

*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.