Chapter 9: Hydrocarbons & Core Organic Reactions (Part-1)

Hydrocarbons are organic compounds containing

A carbon and oxygen
B carbon and nitrogen
C carbon and hydrogen
D carbon only

Alkanes are also known as

A unsaturated hydrocarbons
B olefins
C paraffins
D aromatics

General formula of alkanes is

A CₙH₂ₙ
B CₙH₂ₙ₊₂
C CₙH₂ₙ₋₂
D CₙHₙ

Which hydrocarbon is saturated

A ethene
B ethyne
C benzene
D ethane

Carbon atoms in alkanes are

A sp-hybridised
B sp²-hybridised
C sp³-hybridised
D dsp²-hybridised

Which reaction is characteristic of alkanes

A electrophilic addition
B nucleophilic substitution
C free radical substitution
D electrophilic substitution

Chlorination of methane occurs in presence of

A heat only
B UV light
C catalyst
D acid

In free radical halogenation, the initiation step involves

A formation of carbocation
B homolytic cleavage
C heterolytic cleavage
D rearrangement

Which step determines the rate of free radical substitution

A initiation
B propagation
C termination
D rearrangement

Order of reactivity of halogens towards alkanes is

A F₂ > Cl₂ > Br₂ > I₂
B I₂ > Br₂ > Cl₂ > F₂
C Cl₂ > F₂ > Br₂ > I₂
D Br₂ > Cl₂ > F₂ > I₂

Selectivity in halogenation is highest for

A fluorination
B chlorination
C bromination
D iodination

Major product of chlorination of propane is

A 1-chloropropane
B 2-chloropropane
C equal mixture
D propyl chloride only

Alkenes are unsaturated hydrocarbons containing

A only single bonds
B one triple bond
C one double bond
D aromatic ring

General formula of alkenes is

A CₙH₂ₙ₊₂
B CₙH₂ₙ
C CₙH₂ₙ₋₂
D CₙHₙ

Carbon atoms of double bond are

A sp³
B sp
C sp²
D dsp²

Alkenes mainly undergo

A substitution
B elimination
C addition
D rearrangement

Electrophilic addition occurs due to

A electron-rich alkene
B electron-poor alkene
C free radicals
D nucleophiles

Markovnikov’s rule applies to addition of

A Cl₂
B H₂
C HX
D KMnO₄

According to Markovnikov’s rule, hydrogen attaches to carbon

A with more alkyl groups
B with fewer hydrogens
C with more hydrogens
D randomly

Anti-Markovnikov addition is shown by

A HCl
B HBr in presence of peroxide
C HI
D H₂SO₄

Which reaction follows free radical mechanism in alkenes

A addition of HCl
B hydration
C HBr with peroxide
D ozonolysis

Alkynes contain

A one double bond
B two double bonds
C one triple bond
D aromatic ring

General formula of alkynes is

A CₙH₂ₙ
B CₙH₂ₙ₊₂
C CₙH₂ₙ₋₂
D CₙHₙ

Carbon atoms in alkynes are

A sp³
B sp²
C sp
D dsp²

Terminal alkynes are acidic due to

A inductive effect
B sp-hybridisation
C resonance
D hyperconjugation

Which reagent distinguishes alkene from alkane

A NaOH
B KMnO₄
C HCl
D NH₃

Ozonolysis of alkenes gives

A alcohols
B acids only
C aldehydes/ketones
D alkanes

Dehydration of alcohol produces

A alkane
B alkene
C alkyne
D ether

Elimination reaction involves removal of

A two groups from same carbon
B two groups from adjacent carbons
C one group only
D free radical

Saytzeff’s rule predicts formation of

A least substituted alkene
B most substituted alkene
C terminal alkene
D random product

Elimination using alcoholic KOH follows

A SN1
B SN2
C E2
D radical

Which alkene is most stable

A ethene
B propene
C but-1-ene
D 2-methyl-2-butene

Benzene is classified as

A alkene
B alkyne
C aromatic hydrocarbon
D cycloalkane

Benzene has how many π-electrons

A 2
B 4
C 6
D 8

Benzene mainly undergoes

A addition
B elimination
C electrophilic substitution
D nucleophilic substitution

Which reagent nitrates benzene

A conc. HNO₃
B HNO₃ + H₂SO₄
C NaNO₃
D NO₂

Halogenation of benzene requires

A UV light
B FeCl₃ / AlCl₃
C NaOH
D peroxide

Friedel–Crafts alkylation introduces

A –NO₂
B –SO₃H
C alkyl group
D –CHO

Friedel–Crafts reaction does not occur with

A benzene
B toluene
C nitrobenzene
D anisole

Aromaticity requires

A planarity
B conjugation
C (4n+2) π-electrons
D all of these

Which compound is aromatic

A cyclohexene
B cyclobutadiene
C benzene
D cyclohexane

Anti-aromatic compounds have

A (4n+2) π-electrons
B 4n π-electrons
C no conjugation
D sp³ carbons

Which hydrocarbon is most reactive

A alkane
B alkene
C alkyne
D aromatic

Hydrogenation of alkene gives

A alkyne
B alkane
C alcohol
D ether

Catalyst used in hydrogenation is

A AlCl₃
B FeCl₃
C Ni / Pd / Pt
D H₂SO₄

Bromine water test is positive for

A alkane
B alkene
C aromatic compound
D alcohol

Which compound gives white precipitate with ammoniacal AgNO₃

A ethene
B ethyne
C ethane
D benzene

Which reaction forms alkene from alkyl halide

A substitution
B elimination
C addition
D rearrangement

Most acidic hydrocarbon is

A alkane
B alkene
C alkyne
D benzene

Correct statement is

A Alkanes show addition reactions
B Alkenes show substitution reactions
C Alkynes are less reactive than alkanes
D Benzene prefers substitution over addition