Carbon and Its Compounds – Class 10 Important Questions

Carbon and Its Compounds – Class 10 Important Questions

Fill in the blanks

  1. An atom or a group of atoms that is responsible for the chemical characteristics of an organic compound is called ________.
  2. The general molecular formula of alkynes is ________.
  3. ________ compounds decolorize bromine water.
  4. Dehydration of ethanol by conc. H₂SO₄ forms ________.
  5. 100% pure ethanol is called ________.
  6. Ethanoic acid turns ________ litmus to ________.

Multiple Choice Questions (MCQs)

  1. One mole of which of the following requires 2 moles of hydrogen to form a saturated hydrocarbon?
    a) Only P and Q
    b) Only R and S
    c) Only P and S
    d) Only P, Q and S

  2. Which of the following structures correctly represents the electron dot structure of a Nitrogen molecule?

  3. Assertion (A): Following are the structural isomers of butane.
    Reason (R): Structural isomers have the same molecular formula but they differ in structures.
    Choose the correct option:
    a) Both A and R are true and R is the correct explanation of A.
    b) Both A and R are true but R is not the correct explanation of A.
    c) A is true but R is false.
    d) A is false but R is true.

  4. Assertion (A): Detergents are more effective cleansing agents than soaps in hard water.
    Reason (R): Calcium and magnesium salts of detergents are water-soluble.
    Which option is correct?

  5. The soap molecule has a:
    a) Hydrophilic head and hydrophobic tail
    b) Hydrophobic head and hydrophilic tail
    c) Hydrophilic head and hydrophilic tail
    d) Hydrophobic head and hydrophobic tail

  6. In soap micelles, the ionic end is:
    a) On the surface of the cluster while the carbon chain is in the interior
    b) In the interior while the carbon chain is outside
    c) Both ionic end and carbon chain in interior
    d) Both ionic end and carbon chain outside

Short & Long Answer Questions

  1. From the compounds C₂H₄, CH₃COOH, C₂H₅OH, and C₂H₆ –
  • Identify the saturated hydrocarbon.
  • Identify the organic acid and draw its structure.
  • Which compound on heating with conc. H₂SO₄ at 443K forms ethene? State the role of H₂SO₄.
  • Write the chemical equation when CH₃COOH reacts with C₂H₅OH.

  1. Write balanced chemical equations for:
    i) Neutralization of NaOH with ethanoic acid.
    ii) Reaction of ethanoic acid with NaHCO₃.
    iii) Oxidation of ethanol with acidified K₂Cr₂O₇.
    iv) Combustion of ethanol.

  2. Butter does not decolorize bromine water, whereas cooking oil does. Explain.

  3. An organic compound ‘A’ with molecular formula C₂H₄O₂ reacts with ethanol to form a sweet-smelling compound ‘B’.

  • Identify ‘A’.
  • Write the reaction.
  • Name the process.

  1. Write the name and formula of the 2nd member of the homologous series having general formula CnH₂n.

  2. Compare the structures of benzene and cyclohexane with diagrams.

  3. Write the next homologue of:

  • Propanol (CH₃CH₂CH₂OH)
  • Butanal (CH₃CH₂CH₂CHO)
  1. State reasons why covalent compounds:
  • Are bad conductors of electricity.
  • Have low melting and boiling points.

  1. What is hydrogenation? Mention its industrial application.

  2. Differentiate between ethanol and ethanoic acid (three physical & two chemical properties).

  3. Draw the electron dot structure of chloromethane (CH₃Cl). Also, name the next homologue and give its formula.

  4. A compound with formula C₃H₆ and another with C₄H₁₀ are given. Which one shows addition reaction? Justify.

  5. What will you observe when alkaline KMnO₄ solution is added drop by drop to warm ethanol? Name the compound formed.

  6. Prasad has a saturated alcohol X, C₄H₉OH.

  • Write the formula of the alcohol two places after X in its homologous series.
  • Compare their chemical properties.
  • Write the product formed when this next member is oxidized with acidified K₂Cr₂O₇.

  1. A compound has formula C₂H₆O and is used as a fuel. Identify the compound, its functional group, and write its conversion to ethanoic acid.

  2. Write structural formulae for two possible isomers of C₄H₆. State the reaction conditions to obtain it from 1-butanol.

  3. What is denatured alcohol? Why is ethanol denatured? Mention two uses of ethanol.

  4. Differentiate between saturated and unsaturated hydrocarbons.

  5. Explain the cleansing action of soaps with the help of micelles.

  6. How many possible isomers can be formed with the formula C₆H₁₄? Draw their structures.

  7. Draw structural formulae and electron dot structures of all isomers of C₃H₆O.

  8. When ethanoic acid reacts with sodium hydrogen carbonate, identify the salt and gas formed. Write chemical equation.

  9. Compare the ability of carbon and silicon to exhibit catenation. Give reason.

  10. Define saponification. Write the reaction involved.

  11. Differentiate between soaps and detergents. State why detergents are more effective in hard water.

  12. Name two properties of carbon that result in the large number of carbon compounds.

  13. Define homologous series. Give an example. List its characteristics.

  14. Differentiate between ionic and covalent compounds.


Carbon and Its Compounds – Class 10 Important Questions & Answers

Fill in the blanks

  1. Functional group
  2. CnH₂n–2
  3. Unsaturated
  4. Ethene
  5. Absolute alcohol
  6. Blue, Red

Multiple Choice Questions (MCQs)

  1. (c) Only P and S
  2. Option (b)
  3. (a) Both A and R are true and R is the correct explanation of A
  4. (a) Both A and R are true and R is the correct explanation of A
  5. (a) Hydrophilic head and hydrophobic tail
  6. (a) Ionic end on surface, carbon chain inside the cluster

Short & Long Answer Questions

Q13.

  • Saturated hydrocarbon: C₂H₆ (Ethane)
  • Organic acid: CH₃COOH (Ethanoic acid) – structure: H–C=O with –OH group
  • C₂H₅OH on heating with conc. H₂SO₄ at 443 K forms ethene.
    • Conc. H₂SO₄ acts as a dehydrating agent.
  • Reaction:
    CH₃COOH + C₂H₅OH → CH₃COOC₂H₅ + H₂O

Q14.
i) NaOH + CH₃COOH → CH₃COONa + H₂O
ii) CH₃COOH + NaHCO₃ → CH₃COONa + H₂O + CO₂
iii) C₂H₅OH + [O] → CH₃COOH + H₂O (oxidation by acidified K₂Cr₂O₇)
iv) C₂H₅OH + 3O₂ → 2CO₂ + 3H₂O

Q15.

  • Cooking oil = unsaturated, so it decolorizes bromine water.
  • Butter = saturated, so no reaction with bromine water.

Q16.

  • A = Ethanoic acid (CH₃COOH)
  • Reaction: CH₃COOH + C₂H₅OH → CH₃COOC₂H₅ + H₂O
  • Process: Esterification

Q17.
Second member of CnH₂n series = Propene (C₃H₆)

Q18.

  • Benzene (C₆H₆): planar ring with alternating 3 double bonds.
  • Cyclohexane (C₆H₁₂): hexagonal ring with all single bonds.

Q19.

  • Next homologue of CH₃CH₂CH₂OH = Butanol (C₄H₉OH)
  • Next homologue of CH₃CH₂CH₂CHO = Pentanal (C₅H₁₁CHO)

Q20.
a) Covalent compounds do not form ions → no free electrons → poor conductors.
b) Weak intermolecular forces → low melting and boiling points.

Q21.
Hydrogenation = addition of hydrogen to unsaturated hydrocarbons in presence of Ni/Pd catalyst.

  • Industrial use: conversion of vegetable oil to ghee.

Q22.
Differences between Ethanol & Ethanoic Acid

Property Ethanol Ethanoic Acid
Physical state Liquid Liquid/solid (below 290K)
Smell Spirit-like Vinegar-like
Functional group –OH (alcohol) –COOH (carboxylic acid)
Reaction with NaHCO₃ No reaction CO₂ gas evolved
Effect on litmus Neutral Turns blue litmus red

Q23.

  • Electron dot structure of CH₃Cl:
 H   H
  \ /
   C – Cl
  /
 H
  • Next homologue: C₂H₅Cl (Chloroethane)

Q24.

  • C₃H₆ (Propene) undergoes addition reaction due to double bond.
  • Equation: CH₃–CH=CH₂ + H₂ → CH₃–CH₂–CH₃

Q25.

  • Observation: Purple color of KMnO₄ disappears.
  • Product formed: Ethanoic acid (CH₃COOH)

Q26.
a) Formula of Y (two places after X) = C₆H₁₃OH

  • Molecular mass difference = 28 u
    b) X and Y have similar chemical properties (same functional group –OH).
    c) On oxidation: C₆H₁₃OH → C₅H₁₁COOH (Hexanoic acid)
    General formula: CnH₂n+1COOH

Q27.
Compound: Ethanol (C₂H₅OH)
Functional group: –OH (Alcohol)
Reaction: C₂H₅OH + [O] → CH₃COOH + H₂O

Q28.
Isomers of C₄H₆:

  • HC≡C–CH₂–CH₃ (Butyne)
  • CH₃–C≡C–CH₃ (Butyne)
  • CH₂=C=CH–CH₃ (Butadiene)
    Condition: Heating 1-butanol with conc. H₂SO₄ → dehydration → C₄H₆

Q29.

  • Denatured alcohol = Ethanol mixed with toxic substances like methanol/benzene.
  • Reason: To prevent misuse as a drink.
  • Uses: Solvent, fuel, antiseptic.

Q30.
Saturated hydrocarbons – Single bonds, less reactive, general formula CnH₂n+2
Unsaturated hydrocarbons – Double/triple bonds, more reactive, formula CnH₂n / CnH₂n–2

Q31.

  • Soap molecules have ionic head (hydrophilic) and hydrocarbon tail (hydrophobic).
  • In water, they form micelles: tails trap grease, heads face water → grease removed.

Q32.
C₆H₁₄ has 5 structural isomers:

  • n-hexane
  • 2-methylpentane
  • 3-methylpentane
  • 2,2-dimethylbutane
  • 2,3-dimethylbutane

Q33.
Isomers of C₃H₆O:

  • Propanal (CH₃–CH₂–CHO)
  • Propanone (CH₃–CO–CH₃)

Q34.
Reaction: CH₃COOH + NaHCO₃ → CH₃COONa + H₂O + CO₂

  • Salt (X): Sodium ethanoate
  • Gas (Y): Carbon dioxide

Q35.
Carbon forms a large number of compounds due to:

  1. Catenation – ability to form long chains.
  2. Tetravalency – forms 4 covalent bonds.

Q36.

  • Homologous series: A series of compounds with the same functional group and general formula, differing by –CH₂.
  • Example: Alcohols → CH₃OH, C₂H₅OH, C₃H₇OH
  • Characteristics:
    1. Same functional group
    2. Gradual change in physical properties
    3. Same general formula
    4. Similar chemical properties

Q37.

Ionic Compound Covalent Compound
Formed by transfer of electrons Formed by sharing of electrons
Metal + Non-metal Non-metals only
High melting/boiling point Low melting/boiling point
Conducts electricity (in molten/solution) Poor conductor



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