Free Chemistry of Hydrocarbons MCQs with Answers

• A. RNa+
• B. RCO+
• C. RCOO+
• D. RNO+

Explanation: Acylium ions are cations of the formula RCO +. The carbon-oxygen bond length in these cations is near 1.1 Å (110-112 pm), which is shorter…

• A. C2H6
• B. C2H4
• C. C2H2
• D. C3H6

Explanation: In alkynes,terminal alkyne has acidic hydrogen due to the high level of s character in the sp hybrid orbital, which bonds with the s…

• A. E1 and E2
• B. E1 and SN1
• C. SN1 and SN2
• D. E2and SN1

Explanation: E1 (unimolecular elimination) and SN1 (unimolecular nucleophilic substitution) both involve the same first step: the formation of a…

• A. Functional group isomers
• B. Metamers
• C. Position isomers
• D. Tautomers

Explanation: Propylene glycol and trimethylene glycol are positional isomers. In positional isomers, the same molecular formula is retained, but the…

• A. Only 2-butene
• B. Only 1-butene
• C. 2-butene as the major product
• D. 1-butene as the major product

Explanation: In the dehydrohalogenation of 2-bromobutane with alcoholic KOH, the elimination reaction follows Zaitsev's rule, where the more…

• A. Activates the benzene ring towards electrophilic aromatic substitution
• B. Deactivates the benzene ring towards electrophilic aromatic substitution
• C. Has no effect on the reactivity of the benzene ring
• D. Makes the benzene ring more reactive towards nucleophilic aromatic substitution

Explanation: he -NH₃⁺ group is a strongly electron-withdrawing, deactivating group.It reduces the ring's reactivity and directs substituents to the…

• A. Dehydrohalogenation of vicinal dihalide
• B. Hydrogenation of alkene
• C. Hydrolysis
• D. Hydration of alkene

Explanation: Dehydrohalogenation is a reaction where a vicinal dihalide (a compound with two halogen atoms on adjacent carbon atoms) is converted into…

• A. Propanal
• B. Propanone
• C. Methyl ethyl ether
• D. Butanone

Explanation: Propenol (CH₃CH=CHOH) is a tautomer of propanone (CH₃COCH₃), also known as acetone.

• A. NO2
• B. COOH
• C. Cl
• D. NH3

Explanation: A ring deactivator is a substituent that reduces the reactivity of the benzene ring towards electrophilic substitution reactions.

• A. Methylene chloride
• B. Carbon tetrachloride
• C. Methylene dichloride
• D. Chloroform

Explanation: The chlorination of methane in the presence of UV light and excess chlorine is a substitution reaction that proceeds through a series of…

• A. 2-Bromo-4-chloro-3-lodopentane
• B. 4-Bromo-2-chloro-3-lodopentane
• C. 4 Bromo-2 iodo-3-chloropentane
• D. 2-Chloro-3-iodo-4-bromopentane

Explanation: The IUPAC name is determined by the following rules:1. Number the carbon atoms in the chain, starting from the end closest to the…

• A. C3H8
• B. C2H6
• C. C2H4
• D. C2H2

Explanation: The bond lengths in the given molecules are:- C3H8 (propane): 1.54 Å (single bond)- C2H6 (ethane): 1.53 Å (single bond)- C2H4 (ethylene)…

• A. Cis Isomers
• B. Trans Isomers
• C. Optical Isomers
• D. Geometric isomers

Explanation: Enantiomers are pairs of molecules that are mirror images of each other, but are not superimposable.

• A. Electrons that are free to move around the molecule in the π bonding system above and below the plane of the carbon atoms in the benzene ring
• B. Electrons that are not free to move around the molecule in the π bonding system above and below the plane of the carbon atoms in the benzene ring
• C. Electrons that are free to move around the molecule in the σ bonding system above and below the plane of the carbon atoms in the benzene ring
• D. Electrons that are free to move around the molecule in the π bonding in the benzene ring

Explanation: Electrons that are free to move around the molecule in the π bonding system above and below the plane of the carbon atoms in the benzene…

• A. One
• B. Two
• C. Three
• D. Four - Incorrect. Isobutane does not have four primary carbon atoms.

Explanation: Three - Correct. Isobutane (C₄H₁₀) has three primary carbon atoms, each bonded to only one other carbon.

• A. Phenanthrene
• B. Triphenylmethane
• C. Diphenyl ether
• D. Anthracene

Explanation: Anthracene consists of three linearly fused benzene rings, making it a polycyclic aromatic hydrocarbon.

• A. R-CO-R
• B. R-CO-OR
• C. R-CO-OH
• D. R-COO-R

Explanation: R-CO-OR is the functional group of an ester, which consists of a carbonyl group bonded to an oxygen attached to another alkyl or aryl group.

• A. Malonic acid
• B. Maleic acid
• C. Succinic acid
• D. Lactic acid

Explanation: Maleic acid has a C=C double bond with carboxyl groups attached, allowing for cis-trans isomerism.

• A. dsp3
• B. sp
• C. sp3
• D. dps3
• E. sp2

Explanation: In an ethene molecule, the carbon atoms are sp2 hybridized. One unpaired electron in the p orbital remains unchanged.

• A. Dehydrohalogenation
• B. Wurtz reaction
• C. Dehydration
• D. Catalytic dehydrogenation
• E. Dehalogenation

Explanation: The reaction you described, where 2-chloropropane is heated with Na metal to produce 2,3-dimethyl butane, is a Wurtz reaction.