Kerala SSLC · Chemistry · Class 10

Organic Chemistry: Important Questions with Answers

These are 10 important multiple-choice questions from the Kerala SSLC Chemistry chapter “Organic Chemistry” (Kerala SCERT syllabus). Each one shows the correct answer and a short explanation of why it is right. Try answering before you read the answer. ExamSummary has 10 practice questions on this chapter in total.

  1. Q1.Why does carbon predominantly form covalent bonds instead of ionic bonds?

    • A)Because it gains 4 electrons easily
    • B)Because it loses 4 electrons easily
    • C)Because sharing electrons requires less energy to complete the octet
    • D)Because it forms metallic bonds with non-metals

    Answer: C) Because sharing electrons requires less energy to complete the octet

    Carbon has 4 valence electrons and would require too much energy to gain or lose 4 electrons to form ions. Therefore, it shares electrons with other atoms to achieve a stable noble gas configuration through covalent bonding.

  2. Q2.Which of the following is the general formula for alkenes?

    • A)CnH2n+2
    • B)CnH2n
    • C)CnH2n-2
    • D)CnHn

    Answer: B) CnH2n

    Alkenes are unsaturated hydrocarbons characterized by at least one carbon-carbon double bond. Their molecular formula follows the general pattern CnH2n, distinguishing them from alkanes which follow CnH2n+2.

  3. Q3.Which chemical test is used to distinguish between saturated and unsaturated hydrocarbons?

    • A)Lime water test
    • B)Litmus test
    • C)Bromine water test
    • D)Phenolphthalein test

    Answer: C) Bromine water test

    Unsaturated hydrocarbons contain double or triple bonds that react with bromine water, causing the reddish-brown color to disappear. Saturated hydrocarbons do not react with bromine water under normal conditions, leaving the color unchanged.

  4. Q4.What is the functional group present in ethanoic acid?

    • A)Hydroxyl (-OH)
    • B)Carbonyl (>C=O)
    • C)Carboxyl (-COOH)
    • D)Aldehyde (-CHO)

    Answer: C) Carboxyl (-COOH)

    Ethanoic acid contains a carboxyl group (-COOH) attached to a methyl group. This functional group is responsible for the compound's acidic nature and its characteristic vinegar-like smell.

  5. Q5.When ethanol reacts with ethanoic acid in the presence of concentrated sulfuric acid, what is formed?

    • A)Ethylene
    • B)Ethyl ethanoate
    • C)Sodium ethanoate
    • D)Diethyl ether

    Answer: B) Ethyl ethanoate

    This reaction is known as esterification, producing an ester called ethyl ethanoate which has a fruity smell. Concentrated sulfuric acid acts as a dehydrating agent, removing water produced during the reaction to drive the process forward.

  6. Q6.How many structural isomers does butane (C4H10) possess?

    • A)1
    • B)2
    • C)3
    • D)4

    Answer: B) 2

    Butane exists in two structural forms: n-butane (a straight chain) and isobutane (a branched chain). These two arrangements represent the only possible structural isomers for the molecular formula C4H10.

  7. Q7.Why do soaps not lather well in hard water?

    • A)They react with calcium and magnesium ions to form insoluble precipitates
    • B)They dissolve completely in hot water
    • C)They become acidic in hard water
    • D)They convert into detergents immediately

    Answer: A) They react with calcium and magnesium ions to form insoluble precipitates

    Hard water contains dissolved calcium and magnesium salts that react with soap molecules to form insoluble scum. This precipitate prevents the soap from forming lather and reduces its cleaning effectiveness.

  8. Q8.Which property of carbon allows it to form long chains, branched chains, and rings?

    • A)Allotropy
    • B)Catenation
    • C)Isomerism
    • D)Tetravalency

    Answer: B) Catenation

    Catenation is the unique ability of carbon atoms to link with one another to form very large molecules and complex structures. While tetravalency allows carbon to form four bonds, catenation specifically explains the formation of chains and rings.

  9. Q9.During the saponification process, oils and fats react with sodium hydroxide to produce...

    • A)Alcohol and Water
    • B)Soap and Glycerol
    • C)Salt and Acid
    • D)Ester and Water

    Answer: B) Soap and Glycerol

    Saponification is the alkaline hydrolysis of fats and oils using a strong base like sodium hydroxide. This reaction breaks down the esters in fats to yield sodium salts of fatty acids (soap) and glycerol.

  10. Q10.What is the result of heating ethanol with excess alkaline potassium permanganate?

    • A)It reduces to methane
    • B)It oxidizes to ethanoic acid
    • C)It decomposes into carbon
    • D)It remains chemically unchanged

    Answer: B) It oxidizes to ethanoic acid

    Potassium permanganate acts as a strong oxidizing agent in this reaction, adding oxygen to the ethanol molecule. This process converts ethanol into ethanoic acid by breaking the C-H bond and forming a C-O bond.

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