Organic chemistry questions

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: MCQs on Basic Concepts of Organic Chemistry

MCQ 1

The unique property of carbon to form long chains is called:

A. Isomerism

B. Catenation

C. Hybridization

D. Polymerization

✅ Correct Answer: B. Catenation

Explanation:

Carbon atoms can bond with each other strongly due to catenation, allowing the formation of long chains and rings.

MCQ 2

The hybridization of carbon in methane (CH₄) is:

A. sp

B. sp²

C. sp³

D. dsp²

✅ Correct Answer: C. sp³

Explanation:

In methane, carbon forms four single bonds arranged tetrahedrally, indicating sp³ hybridization.

: MCQs on Hydrocarbons (NEET/JEE Level)

MCQ 3

Which hydrocarbon undergoes addition reactions?

A. Alkane

B. Alkene

C. Alkyl halide

D. Alcohol

✅ Correct Answer: B. Alkene

Explanation:

Alkenes contain a C=C double bond, which breaks during addition reactions.

MCQ 4

Which of the following is an unsaturated hydrocarbon?

A. Ethane

B. Propane

C. Ethene

D. Methane

✅ Correct Answer: C. Ethene

Explanation:

Ethene contains a double bond and is therefore an unsaturated hydrocarbon.

: MCQs on Functional Groups

MCQ 5

The functional group present in aldehydes is:

A. –COOH

B. –CO–

C. –CHO

D. –OH

✅ Correct Answer: C. –CHO

Explanation:

Aldehydes are characterized by the presence of the –CHO functional group.

MCQ 6

Which compound will give effervescence with sodium bicarbonate?

A. Alcohol

B. Aldehyde

C. Ketone

D. Carboxylic acid

✅ Correct Answer: D. Carboxylic acid

Explanation:

Carboxylic acids react with NaHCO₃ to produce CO₂ gas, causing effervescence.

: MCQs on Isomerism

MCQ 7

Isomers have the same:

A. Structural formula

B. Empirical formula

C. Molecular formula

D. Functional group

✅ Correct Answer: C. Molecular formula

Explanation:

Isomers have identical molecular formulas but different arrangements of atoms.

MCQ 8

Chain isomerism is shown by:

A. Ethane

B. Butane

C. Methane

D. Ethene

✅ Correct Answer: B. Butane

Explanation:

Butane exists as n-butane and isobutane, showing chain isomerism.

: MCQs on Alcohols, Aldehydes & Ketones

MCQ 9

Oxidation of a primary alcohol gives:

A. Ketone

B. Ether

C. Aldehyde

D. Alkane

✅ Correct Answer: C. Aldehyde

Explanation:

Primary alcohols oxidize first to aldehydes and then to carboxylic acids.

MCQ 10

Which reagent is used to distinguish aldehyde from ketone?

A. Fehling’s solution

B. Sodium hydroxide

C. HCl

D. Alcoholic KOH

✅ Correct Answer: A. Fehling’s solution

Explanation:

Aldehydes reduce Fehling’s solution, while ketones do not.

: MCQs on Amines

MCQ 11

The basic nature of amines is due to:

A. Presence of hydrogen

B. Lone pair of electrons on nitrogen

C. High molecular mass

D. Alkyl group

✅ Correct Answer: B. Lone pair of electrons on nitrogen

Explanation:

The lone pair on nitrogen allows amines to accept protons, making them basic.