75 free MCQs on Hydrocarbons, each with its own worked answer and explanation. The simplest organic compounds made only of carbon and hydrogen. Covers alkanes, alkenes, alkynes, and aromatic compounds like benzene. Learn preparation methods, key reactions, and physical properties.
Take the timed Hydrocarbons chapterwise test →75 practice questions on Hydrocarbons, sorted Easy → Hard. Try each one first, then open its answer page for the worked explanation. Want the full theory first? Read the Hydrocarbons notes.
Going from a single to a triple bond between carbons increases the s-character of hybridisation (sp³→sp²→sp), shortening the bond and locking the geometry, while increasing π-bond reactivity (alkenes and alkynes readily undergo addition reactions that alkanes don't).
Q1.
Decarboxylation of sodium acetate with soda lime produces:
Q2.
Which is the simplest alkene capable of showing cis-trans (geometrical) isomerism?
Q3.
Kolbe's electrolysis of an aqueous solution of sodium acetate liberates which gas at the anode?
Q4.
Among n-pentane, isopentane and neopentane, which has the lowest boiling point?
Q5.
According to Markovnikov's rule, when HBr adds to propene the hydrogen atom attaches to:
Q6.
Which hydrocarbon contains only single bonds?
Q7.
What is the general formula of alkenes?
Q8.
Which hydrocarbon contains a triple bond?
Q10.
Which gas is the major component of natural gas?
Q11.
Petroleum is primarily a mixture of:
Q13.
Combustion of hydrocarbons produces:
Q14.
What is the hybridisation of carbon in methane?
Q15.
Which process breaks large hydrocarbons into smaller molecules?
Q16.
Which hydrocarbon has the formula C<sub>2</sub>H<sub>4</sub>?
Q17.
Which hydrocarbon gives a sooty flame?
Q18.
What is the IUPAC name of C<sub>3</sub>H<sub>8</sub>?
Q19.
Which test identifies unsaturation in hydrocarbons?
Q22.
What is the bond angle in sp<sup>2</sup> hybridised carbon?
Q23.
Which hydrocarbon contains only carbon and hydrogen?
Q24.
What is the general formula of alkynes?
Q25.
Which hydrocarbon has the highest boiling point among these?
Q26.
Markovnikov addition of HBr to but-1-ene gives which major product?
Q27.
Ozonolysis (reductive) of but-2-ene gives:
Q28.
2-Bromobutane on treatment with alcoholic KOH gives which major alkene?
Q29.
How many structurally isomeric monochlorination products can 2-methylbutane form?
Q30.
Which reagent converts propyne into propanone (acetone)?
Q31.
Which rule predicts the major product during addition of HX to an unsymmetrical alkene?
Q32.
Anti-Markovnikov addition occurs in presence of:
Q33.
Ozonolysis of ethene produces:
Q34.
Hydrogenation of alkenes is carried out in presence of:
Q35.
Which type of reaction is mainly shown by alkenes?
Q36.
What is formed when ethyne reacts with excess hydrogen?
Q37.
Which reagent is used for bromination of benzene?
Q38.
What is the hybridisation of carbon atoms in benzene?
Q39.
Which hydrocarbon undergoes electrophilic aromatic substitution?
Q40.
Friedel-Crafts alkylation requires which catalyst?
Q41.
Addition of HBr to propene in presence of peroxide gives:
Q42.
Which intermediate is formed during electrophilic addition to alkenes?
Q43.
Which compound gives acetaldehyde on ozonolysis?
Q44.
What is the major product of nitration of benzene?
Q45.
Which reagent converts alkene into alkane?
Q46.
Which hydrocarbon undergoes polymerisation easily?
Q48.
Which reaction converts benzene into ethylbenzene?
Q49.
What is the product formed when ethene reacts with bromine water?
Q50.
Which reaction confirms unsaturation in hydrocarbons?
Q51.
An alkene X on reductive ozonolysis gives a mixture of propanone (acetone) and ethanal (acetaldehyde). X is:
Q52.
The peroxide (Kharasch) effect giving anti-Markovnikov addition is observed only with which hydrogen halide?
Q53.
Addition of HCl to 3-methylbut-1-ene gives mainly 2-chloro-2-methylbutane because of:
Q54.
Which of the following is the most reactive towards electrophilic aromatic substitution?
Q55.
Birch reduction of toluene (Na in liquid NH<sub>3</sub> with alcohol) gives mainly:
Q56.
What is the first intermediate formed during electrophilic addition of HBr to propene?
Q57.
Which carbocation is formed during Markovnikov addition of HBr to propene?
Q58.
Birch reduction converts benzene into:
Q59.
Which reagent is used in Birch reduction?
Q60.
Baeyer strain theory explains instability in cyclic compounds due to:
Q61.
Why are terminal alkynes acidic?
Q62.
Which compound can react with sodium metal to release hydrogen gas?
Q63.
Which group directs incoming electrophiles to ortho and para positions?
Q64.
Which substituent is meta directing?
Q65.
What is the major product when benzene reacts with chlorine in presence of FeCl<sub>3</sub>?
Q66.
Which intermediate forms during nitration of benzene?
Q67.
Ozonolysis of 2-methylpropene gives:
Q68.
Cyclopentadienyl anion is aromatic because it contains:
Q69.
Which hydrocarbon undergoes free radical substitution easily?
Q70.
What is the major product of Wurtz reaction using two molecules of ethyl bromide?
Q71.
Which species acts as the electrophile in halogenation of benzene?
Q72.
Which compound is antiaromatic?
Q73.
Which alkene gives acetone on ozonolysis?
Q74.
Which conformation of cyclohexane has the highest strain?
Q75.
What is the product formed when ethyne reacts with excess bromine?
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