#boiling points

CHEMISTRY

Which of the following is the correct order of boiling points?

Hydrogen bonding increases the boiling point. Alcohols have higher boiling points than ethers due to strong intermolecular hydrogen bonding. This follows from latest NCERT 2026-27 principle explaining the concept clearly for NEET students in simple steps as per rationalized syllabus.

Ref: NCERT Chemistry Textbook - Latest Edition for Academic Session 2026-27 (Rationalized Textbook for Class XI and XII)Topic: Mole concept, atomic structure, chemical formulas like H₂O, CO₂, CH₃CH₂NH₂ and periodic trends.

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Reaction with Nitrous Acid and Diazonium Salts - Part 1

Which of the following is a correct order of boiling points?

Primary amines have higher boiling points than tertiary amines due to hydrogen bonding. Thus, CH₃CH₂NH₂ (primary) > (CH₃)₃N (tertiary), as per the PDF’s physical properties.

Ref: NCERT Class 12 Chemistry > Chapter 13: Amines > Topic: Reaction with Nitrous Acid and Diazonium Salts - Part 1

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Reactions due to α-Hydrogen - Aldol, Cannizzaro and Acidity of Carboxylic Acids

Which compound has the highest boiling point among aldehydes with five carbon atoms?

Pentanal (CH₃CH₂CH₂CH₂CHO), a straight-chain aldehyde, has stronger dipole-dipole interactions than branched isomers like 2-methylbutanal, giving it the highest boiling point.

Ref: NCERT Class 12 Chemistry > Chapter 12: Aldehydes, Ketones and Carboxylic Acids > Topic: Reactions due to α-Hydrogen - Aldol, Cannizzaro and Acidity of Carboxylic Acids

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Reactions due to α-Hydrogen - Aldol, Cannizzaro and Acidity of Carboxylic Acids

Arrange in decreasing order of boiling points: CH₃CHO, CH₃COOH, CH₃CH₂OH.

Boiling points depend on intermolecular forces: CH₃COOH (strong H-bonding) > CH₃CH₂OH (H-bonding) > CH₃CHO (dipole-dipole).

Ref: NCERT Class 12 Chemistry > Chapter 12: Aldehydes, Ketones and Carboxylic Acids > Topic: Reactions due to α-Hydrogen - Aldol, Cannizzaro and Acidity of Carboxylic Acids

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Reactions due to α-Hydrogen - Aldol, Cannizzaro and Acidity of Carboxylic Acids

Arrange in decreasing order of boiling points: Hexanal, Hexan-1-ol, Pentanoic acid.

Boiling points: Pentanoic acid (strong H-bonding) > Hexan-1-ol (H-bonding) > Hexanal (dipole-dipole).

Ref: NCERT Class 12 Chemistry > Chapter 12: Aldehydes, Ketones and Carboxylic Acids > Topic: Reactions due to α-Hydrogen - Aldol, Cannizzaro and Acidity of Carboxylic Acids

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Chemical Reactions - Reduction, Oxidation and Tests - Tollens, Fehling, Iodoform

Arrange in decreasing order of boiling points: Pentanal, Pentanoic acid, 2-Methylbutan-1-ol.

Boiling points: Pentanoic acid (strong H-bonding) > 2-Methylbutan-1-ol (H-bonding) > Pentanal (dipole-dipole).

Ref: NCERT Class 12 Chemistry > Chapter 12: Aldehydes, Ketones and Carboxylic Acids > Topic: Chemical Reactions - Reduction, Oxidation and Tests - Tollens, Fehling, Iodoform

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Preparation of Alcohols - from Alkenes Haloalkanes Carbonyls Grignard

Why does ethane-1,2-diol have a higher boiling point than ethanol?

Ethane-1,2-diol (CH₂OH-CH₂OH) has two -OH groups, leading to more extensive hydrogen bonding than ethanol (CH₃CH₂OH), which has one -OH group, increasing its boiling point.

Ref: NCERT Class 12 Chemistry > Chapter 7: Alcohols, Phenols and Ethers > Topic: Preparation of Alcohols - from Alkenes Haloalkanes Carbonyls Grignard

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Purification Methods - Crystallization Distillation Chromatography

Which method is used to separate a mixture of two liquids with different boiling points?

Distillation separates liquids based on differences in their boiling points, vaporizing the lower boiling point liquid first.

Ref: NCERT Class 11 Chemistry > Chapter 8: Organic Chemistry - Some Basic Principles and Techniques > Topic: Purification Methods - Crystallization Distillation Chromatography

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Purification Methods - Crystallization Distillation Chromatography

Which purification technique is most suitable for separating a mixture of CHCl₃ (b.p. 61°C) and CH₃COCH₃ (b.p. 56°C)?

Fractional distillation separates liquids with close boiling points (difference < 25°C) using a fractionating column.

Ref: NCERT Class 11 Chemistry > Chapter 8: Organic Chemistry - Some Basic Principles and Techniques > Topic: Purification Methods - Crystallization Distillation Chromatography

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Purification Methods - Crystallization Distillation Chromatography

A mixture of two liquids with boiling points 75°C and 90°C is separated efficiently on a large scale using which techniq

A 15°C difference (< 25°C) requires fractional distillation for efficient large-scale separation due to close boiling points.

Ref: NCERT Class 11 Chemistry > Chapter 8: Organic Chemistry - Some Basic Principles and Techniques > Topic: Purification Methods - Crystallization Distillation Chromatography

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Purification Methods - Crystallization Distillation Chromatography

Which purification method is used for a liquid mixture with boiling points of 78°C and 82°C?

Fractional distillation is used for liquids with close boiling points (< 25°C difference), like 78°C and 82°C.

Ref: NCERT Class 11 Chemistry > Chapter 8: Organic Chemistry - Some Basic Principles and Techniques > Topic: Purification Methods - Crystallization Distillation Chromatography

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Purification Methods - Crystallization Distillation Chromatography

Which separation technique is most suitable for a mixture of two liquids with boiling points 65°C and 95°C, where one is

Differential extraction can exploit solubility differences (e.g., water vs. organic solvent), while the 30°C boiling point difference also allows simple distillation, but solubility makes extraction more specific.

Ref: NCERT Class 11 Chemistry > Chapter 8: Organic Chemistry - Some Basic Principles and Techniques > Topic: Purification Methods - Crystallization Distillation Chromatography

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