Explanation

• Glacial acetic acid is nearly pure, water-free acetic acid (CH₃COOH).
• It is called “glacial” because it freezes at approximately 16.6°C, forming ice-like crystals.
• Ordinary vinegar is a dilute aqueous solution of acetic acid, usually containing about 4–8% acetic acid.
• Acetic anhydride is a different chemical compound.

Last verified on 02-11-2026

Explanation

• Tollens' test is also called the silver mirror test.
• It is used to identify aldehydes because they reduce silver ions (Ag⁺) to metallic silver.
• A shiny silver coating forms on the inner surface of the test tube.
• The reagent contains ammoniacal silver nitrate, known as Tollens' reagent.

Last verified on 02-11-2026

Explanation

• Cannizzaro reaction is a self-oxidation-reduction (disproportionation) reaction.
• It occurs in aldehydes that do not contain an alpha-hydrogen atom, in the presence of a concentrated alkali.
• One aldehyde molecule is oxidized into a carboxylate salt, while another is reduced into an alcohol.
• Example: Benzaldehyde produces benzyl alcohol and sodium benzoate with concentrated NaOH.

Last verified on 02-11-2026

Explanation

• Ethyl alcohol (ethanol, C₂H₅OH) undergoes oxidation to form acetic acid (CH₃COOH).
• Potassium dichromate in acidic medium acts as a strong oxidizing agent.
• Acetaldehyde is an intermediate product during the oxidation of ethanol to acetic acid.
• Complete oxidation under suitable conditions produces acetic acid.

Last verified on 02-11-2026

Explanation

Explanation

• German chemist August Kekulé proposed the cyclic structure of benzene in 1865.
• He suggested that benzene (C₆H₆) consists of a six-carbon ring with alternating single and double bonds.
• The benzene ring is also known as the Kekulé structure.

Last verified on 02-11-2026

Explanation

• Ethene (C₂H₄) is an unsaturated hydrocarbon containing a carbon-carbon double bond.
• It decolourises cold, dilute alkaline KMnO₄ solution by undergoing oxidation.
• This test is known as Baeyer's test.
• It is used to detect unsaturation.

Last verified on 02-11-2026

Explanation

• Raney nickel is a porous form of nickel used as a catalyst in hydrogenation reactions.
• It helps add hydrogen (H₂) to unsaturated compounds, converting double or triple bonds into single bonds.
• It is commonly used to convert alkenes into alkanes and in the reduction of various organic compounds.

Last verified on 02-11-2026

Explanation

• Liquid bromine test: Unsaturated compounds decolourise reddish-brown bromine solution due to addition across double or triple bonds.
• Baeyer's reagent: Cold, dilute alkaline potassium permanganate (KMnO₄) is decolourised by unsaturated compounds.
• Both tests are commonly used to detect carbon-carbon double and triple bonds.

Additional information:

• Fehling's solution is mainly used to test reducing sugars and aldehydes.

Last verified on 02-11-2026

Explanation

• The percentage of ethene (ethylene) in coal gas is approximately 2%.

Coal gas is a mixture of several gases, typically composed of:

• • Hydrogen: ~50%
• • Methane: ~30%
• • Carbon Monoxide: ~10%
• • Ethene (Ethylene): ~2%
• • Other gases (Nitrogen, Oxygen, Carbon Dioxide): Remaining %

Last verified on 02-11-2026