Free Chemistry of Hydrocarbons MCQs with Answers

• A. n-pentane, 2-methyl butane, 2,2-dimethylpropane
• B. n-pentane, 2-methyl butane, 2,3-dimethyl butane
• C. n-pentane, 3-methyl butane, 2,2-dimethylpentane
• D. n-pentane, 2-methyl pentane, 2,2-dimethyl propane

Explanation: Pentane has 3 isomers which are as follows; CH3-CH2-CH2-CH2-CH3 (n-pentane) CH3-CH(CH3)-CH2-CH3 (2-methyl butane) CH3-C(CH3)2-CH3…

• A. functional group isomerism
• B. Chain isomerism
• C. Position isomerism
• D. Metamerism

Explanation: Aldehydes and ketones are functional group isomers of each other. Hence, option A is correct.

• A. Functional group
• B. Position of functional group
• C. Shifting of proton
• D. Distribution of carbon atoms around the functional group

Explanation: Metamers are a type of structural isomerism where molecules have the same molecular formula but differ in the distribution of carbon atoms…

• A. Functional group
• B. Position
• C. Chain
• D. Metamerism

Explanation: In a compound with the molecular formula C2H6O, which corresponds to ethanol (CH3CH2OH) as well as dimethyl ether ( CH3-O-CH3), the type…

• A. Dil:NaOH
• B. Alc: KOH
• C. NaOH +Cao
• D. Na/Ether

Explanation: Benzene is prepared in the laboratory by the decarboxylation of sodium benzoate in the presence of sodium hydroxide and calcium oxide (a…

• A. CH3 - CH3
• B. CH2 = CH2
• C. CH≡CH
• D. C6H6

Explanation: Out of the given options, CH2=CH2 represents ethene, which is an alkene.

• A. enyne
• B. ene
• C. упе
• D. ane

Explanation: When both double and triple bonds are present in a compound, the ending "-enyne" is used. So, the compound is referred to as an enyne.

• A. Ethane
• B. Ethene
• C. Benzene
• D. Ethyne

Explanation: Ethane is an alkane and is relatively unreactive due to its single C-C and C-H bonds.

• A. Alkanes > Alkynes > Alkenes
• B. Alkenes > Alkanes > Alkynes
• C. Alkynes > Alkenes > Alkanes
• D. Alkenes > Alkynes > Alkanes

Explanation: Alkenes are generally more reactive than alkanes, and alkynes are typically the most reactive among hydrocarbons due to the presence of…

• A. Halogenation
• B. Friedel-Crafts acylation reaction
• C. Friedel-Crafts alkylation reaction
• D. Sulphonation

Explanation: The type of reaction where benzene is treated with an alkyl halide in the presence of anhydrous ammonium chloride to form an alkylbenzene…

• A. AgNO3 + NH4OH
• B. 1% alkaline dilute KMnO4
• C. Br2/CCI4
• D. K2Cr2O7 +H2SO4

Explanation: AgNO3 + NH4OH and K2Cr2O7 + H2SO4 are the reagents that can effectively distinguish between 1-pentyne and 2-pentyne.

• A. 1-bromobutane
• B. 2-bromobutane
• C. 2,3-dibromobutane
• D. 1,3-dibromobutane

Explanation: The addition of HBr to 2-butene forms 2-bromobutane. Since it's a symmetrical alkene, it does not follow Markonivkov rules.

• A. Substitution
• B. Combustion
• C. Hydrogenation
• D. Addition

Explanation: The correct option is D. Addition. Under suitable conditions, alkanes do not readily undergo addition reactions.

• A. 1 > 2 > 3
• B. 3 > 2 > 1
• C. 2> 3 > 1
• D. 3 > 1 > 2

Explanation: 1. CH₃CH₂CH₂⁺ (Primary carbocation):This is a primary carbocation, meaning it has one alkyl group attached directly to the positively…

• A. Propane
• B. Propene
• C. Ethyl isopropyl ether
• D. All are formed

Explanation: The correct major product when 2-bromopropane reacts with sodium ethoxide is B. Propene (propylene).

• A. Passing a mixture of propyne and steam over a catalyst, magnesium at 420°C
• B. Passing a mixture of propyne and ethanol over a catalyst, zinc chromate
• C. Boiling propyne with water in the presence of HgSO₄ and H₂SO₄
• D. Treating propyne with iodine and NaOH

Explanation: The correct option is C; the explanation is already given.

• A. Dehalogenation of Vicinal Dihalides in the Presence of Methanol.
• B. Dehydration of alcohols in the presence of Al₂O₃ at 340-450 degrees centigrade.
• C. Dehalogenation of Vicinal Dihalides in the Presence of Strong Base.
• D. Electrolysis of unsaturated dicarboxylic acid salts.

Explanation: A strong base (like alcoholic KOH or NaNH₂) can remove two equivalents of HX from a vicinal dihalide to yield an alkyne.

• A. To increase activation energy
• B. To enhance hydrogenation of alkene
• C. To produce cis alkene
• D. To start polymerisation reaction

Explanation: Lindlar's catalyst is specifically designed for the partial hydrogenation of alkynes to form cis-alkenes.

• A. -COR
• B. -NO2
• C. -CHO
• D. -NR2

Explanation: Examples of meta- directors include nitriles, carbonyl compounds (such as aldehydes, ketones, and esters), sulfones, electron-deficient…

• A. Catechol
• B. Resorcinol
• C. Hydroquinone
• D. O-cersol

Explanation: Resorcinol is a 1,3-isomer (or meta-isomer) of benzenediol with the formula C6H4(OH)2.