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JEE • CHEMISTRY • HYDROCARBONS

Hydrocarbons practice · Easy

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These sets use single-correct-answer MCQs. They do not cover every JEE Main or JEE Advanced question format and are not full-length mock papers.

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Showing 1-30 of 138 questions

1 Easy

1 of 138

Understanding +4 | -1

In benzene, there is a delocalisation of π-electrons. Hence, each π-electron is attached by….carbon nuclei.

View answer and explanation

Correct option: C

Option C (6) is correct because in benzene, the π-electrons are delocalized over all six carbon atoms in the ring.

2 Easy

2 of 138

Understanding +4 | -1

Which statement is false?

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Correct option: C

Chlorination of methane follows an ionic mechanism

Option C is correct because chlorination of methane follows a free radical mechanism, not an ionic mechanism.

3 Easy

3 of 138

Analyzing +4 | -1

Assertion (A) In comparison to ethyl chloride, it is not easy to carry outnucleophilic substitution on vinyl chloride.

Reason (R) Vinyl group is an electron donating.

View answer and explanation

Correct option: C

If Assertion is true but Reason is false.

Option C is correct because nucleophilic substitution is difficult on vinyl chloride due to resonance, which gives the C-Cl bond partial double bond character, but the vinyl group is electron-withdrawing, not donating.

4 Easy

4 of 138

Remembering +4 | -1

Fischer-Tropsch process is used in the manufacture of:

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Correct option: A

Synthetic petrol

Option A (Synthetic petrol) is correct because the Fischer-Tropsch process is a chemical reaction used to produce synthetic hydrocarbons, which can be refined into synthetic petrol (gasoline).

5 Easy

5 of 138

Understanding +4 | -1

Among the following group, which deactivates benzene ring for electrophilic substitution:

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Correct option: D

Chlorine

Option D (Chlorine) is correct because halogens deactivate the benzene ring due to their strong -I effect, even though they are ortho- and para-directing.

6 Easy

6 of 138

Understanding +4 | -1

Which of the following annulenes is anti-aromatic?

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Correct option: B

Cyclobutadiene

Option B is correct. Cyclobutadiene is anti-aromatic because it is cyclic, planar, has 4π electrons (which is not a Hückel number), and has alternating single and double bonds.

7 Easy

7 of 138

Remembering +4 | -1

By coaltar distillation which is not obtained?

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Correct option: D

Mobil oil

Option D (Mobil oil) is correct because light oil, middle oil, and heavy oil are all obtained through coal tar distillation, while mobil oil is not.

8 Easy

8 of 138

Remembering +4 | -1

An anaestheticnarcylene is commercial name of:

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Correct option: B

{\mathrm{C}_2}{\mathrm{H}_2}

Option B (

{\mathrm{C}_2}{\mathrm{H}_2}

) is correct because narcylene is the commercial name for acetylene, which was historically used as an anesthetic.

9 Easy

9 of 138

Remembering +4 | -1

The main constituent of light oil fraction is:

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Correct option: A

Benzene

Option A (Benzene) is correct because benzene (

C_6H_6

) is the main constituent of the light oil fraction obtained from coal tar distillation.

10 Easy

10 of 138

Remembering +4 | -1

Benzene is converted to toluene by:

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Correct option: A

Friedel-Crafts reaction

Option A (Friedel-Crafts reaction) is correct because the Friedel-Crafts alkylation reaction is used to add alkyl groups, such as methyl groups, to aromatic rings like benzene, converting it to toluene.

11 Easy

11 of 138

Understanding +4 | -1

Which of the following compounds can be best prepared by Wurtz reaction?

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Correct option: D

n-butane

Option B (2 molecules of benzoic acid, 1 molecule of benzoic acid and 1 molecule of ethanoic acid) is correct because it shows the hydrolysis products of the given anhydrides.

12 Easy

12 of 138

Understanding +4 | -1

Assertion (A): Acetylene does not react with

\mathrm{NaOH}

Reason (R): Acetylene has sp hybridised carbons.

View answer and explanation

Correct option: B

Both A

\&

R are correct but R is not the correct explanation of A

Option B (Both A

\& R are correct but R is not the correct explanation of A) is correct because acetylene is a weak acid and does not react with NaOH, and it does have sp hybridized carbons, but the hybridization is not the reason for its lack of reactivity with NaOH.

13 Easy

13 of 138

Understanding +4 | -1

Which of the following compound is not prepared by Kolbe’s electrolytic method

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Correct option: C

C{H_4}

Option C is correct because Kolbe's electrolytic method involves the electrolysis of an aqueous solution of sodium or potassium salts of carboxylic acids, leading to the formation of alkanes, alkenes, or alkynes with an even number of carbon atoms. Methane (CH4) cannot be prepared this way.

14 Easy

14 of 138

Understanding +4 | -1

Butyne-1 and butyne-2 can be distinguished by:

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Correct option: D

Ammoniacal cuprous chloride

Option D (Ammoniacal cuprous chloride) is correct because terminal alkynes (butyne-1) react with ammoniacal cuprous chloride to form a red precipitate, while internal alkynes (butyne-2) do not.

15 Easy

15 of 138

Remembering +4 | -1

The number of

\pi

-electrons in benzene molecule is :

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Correct option: A

3 ×2

Option A (3 ×2) is correct because benzene has 6 pi electrons, which can be represented as 3 double bonds, hence 3 x 2 = 6 pi electrons.

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16 Easy

16 of 138

Remembering +4 | -1

Petrol or gasoline used as an automobile fuel is a mixture of:

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Correct option: A

Hydrocarbons

Option A (Hydrocarbons) is correct because petrol or gasoline is primarily a mixture of various hydrocarbons, mainly alkanes, with carbon chain lengths typically ranging from C6 to C11.

17 Easy

17 of 138

Understanding +4 | -1

Which is true for a chain-terminating step?

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Correct option: C

E_{\text {act}}=0

Option C (

E_{\text {act}}=0

) is correct because chain-terminating steps involve the combination of radicals, which requires little to no activation energy.

18 Easy

18 of 138

Remembering +4 | -1

Ethylene is used for:

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Correct option: D

All are correct

Option D (All are correct) is correct because ethylene is used for ripening of food, preparing ethylene oxide, and preparing ethylene chloride.

19 Easy

19 of 138

Understanding +4 | -1

Number of acidic hydrogen atom in butyne-1 is:

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Correct option: C

Option C (1) is correct because butyne-1 has only one hydrogen atom directly attached to the sp hybridized carbon.

20 Easy

20 of 138

Analyzing +4 | -1

Assertion (A): Acetylene reacts with sodamide to evolve

\mathrm{H}_2

gas.
Reason (R): Acetylene is a weaker acid than ammonia

View answer and explanation

Correct option: C

A is correct but R is incorrect

Option C is correct. Acetylene reacts with sodamide to produce H2 gas, but acetylene is a stronger acid than ammonia, not weaker.

21 Easy

21 of 138

Understanding +4 | -1

Mark the correct statement

View answer and explanation

Correct option: D

Ethane has an infinite number of conformation of which the staggered conformation is possessed by majority of the molecules at room temperature

Option D (Ethane has an infinite number of conformation of which the staggered conformation is possessed by majority of the molecules at room temperature) is correct because the staggered conformation is more stable and thus more populated at room temperature.

22 Easy

22 of 138

Remembering +4 | -1

Method of converting high boiling hydrocarbons into low boiling hydrocarbons is called:

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Correct option: C

Cracking

The correct answer is C (Cracking) because cracking is the process of breaking down large hydrocarbon molecules into smaller, more volatile ones.

23 Easy

23 of 138

Understanding +4 | -1

Ethylene reacts with dil.

{\mathrm{H}_2}\mathrm{S}{\mathrm{O}_4}

in presence of

\mathrm{HgS}{\mathrm{O}_4}

to give:

View answer and explanation

Correct option: B

Ethanol

Option B (Ethanol) is correct because the reaction of ethylene with dilute sulfuric acid in the presence of mercuric sulfate leads to the addition of water, forming ethanol.

24 Easy

24 of 138

Understanding +4 | -1

The most stable conformation of butane is:

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Correct option: B

Staggered

Option B is correct because the staggered conformation of butane is the most stable due to minimized torsional strain and steric hindrance.

25 Easy

25 of 138

Remembering +4 | -1

Which product is not obtained by heating wood or coal in the absence of air?

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Correct option: D

Wax

Option D (Wax) is correct because Wax is not obtained by heating wood or coal in the absence of air.

26 Easy

26 of 138

Application +4 | -1

A fuel contains 25%

n

-heptane and 75% iso-octane. Its octane number is:

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Correct option: B

Option B (75) is correct because the octane number is defined as the percentage of iso-octane in the fuel mixture.

27 Easy

27 of 138

Understanding +4 | -1

The most reactive halogen in the halogenation of alkanes is:

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Correct option: A

\mathrm{C}{\mathrm{l}_2}

Option A (

\mathrm{C}{\mathrm{l}_2}

) is correct because chlorine is the most reactive halogen in the halogenation of alkanes due to its lower bond dissociation energy compared to bromine and iodine.

28 Easy

28 of 138

Analyzing +4 | -1

Which isomeric dibromotoluene is most difficult to make from toluene?

View answer and explanation

Correct option: C

3, 5

Option C (3, 5) is correct because the methyl group is ortho- and para-directing, making meta-substitution (3,5) less favorable.

29 Easy

29 of 138

Application +4 | -1

The IUPAC name of

C{H_3} - \mathop {CH}\limits^{\begin{array}{cccccccccccccccccccc} {C{H_3}} \\ {|\,\,\,\,\,\,\,\,} \end{array}} - C{H_2}C{H_2}C{H_3}

View answer and explanation

Correct option: B

2-methylpentane

Option B (2-methylpentane) is correct because it follows IUPAC naming rules, prioritizing the lowest possible number for the substituent.

30 Easy

30 of 138

Application +4 | -1

If an alkane has number of carbon atoms equal to

n,

then the
number of moles of oxygen required for its complete
combustion is:

View answer and explanation

Correct option: A

\frac{3n+1}{2}

Option A (

\frac{3n+1}{2}

) is correct because it represents the stoichiometric coefficient of oxygen in the balanced combustion equation for an alkane.

Revision notes and key takeaways

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Key Takeaways

✓ This set contains 138 single-correct-answer MCQs on HYDROCARBONS.
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