Assertion and Reason Questions for CBSE Class 10 Science Chapter 4: Carbon and Its Compounds

Carbon and Its Compounds

  1. Assertion (A): Carbon forms covalent bonds by sharing its valence electrons.
    Reason (R): Carbon has four valence electrons and requires eight to complete its octet.
    Answer: Both A and R are true, and R is the correct explanation of A.
    Explanation: Carbon forms covalent bonds by sharing electrons to complete its octet.
  2. Assertion (A): Carbon forms a large number of compounds due to its catenation property.
    Reason (R): Catenation is the ability of an element to form bonds with atoms of different elements.
    Answer: A is true, but R is false.
    Explanation: Catenation refers to the ability of carbon to form bonds with other carbon atoms, not different elements.
  3. Assertion (A): Ethene is more reactive than ethane.
    Reason (R): Ethene has a double bond, while ethane has a single bond between carbon atoms.
    Answer: Both A and R are true, and R is the correct explanation of A.
    Explanation: The presence of a double bond in ethene makes it more reactive than ethane.
  4. Assertion (A): All alkanes are saturated hydrocarbons.
    Reason (R): Saturated hydrocarbons contain only single covalent bonds between carbon atoms.
    Answer: Both A and R are true, and R is the correct explanation of A.
    Explanation: Alkanes have only single covalent bonds, making them saturated hydrocarbons.
  5. Assertion (A): Functional groups determine the chemical properties of organic compounds.
    Reason (R): Functional groups are specific atoms or groups of atoms that replace hydrogen in hydrocarbons.
    Answer: Both A and R are true, and R is the correct explanation of A.
    Explanation: Functional groups influence the chemical behavior of organic compounds by replacing hydrogen atoms.
  6. Assertion (A): Methanol and ethanol are members of the homologous series of alcohols.
    Reason (R): Members of a homologous series have the same functional group and differ by a CH₂ unit.
    Answer: Both A and R are true, and R is the correct explanation of A.
    Explanation: Methanol and ethanol are part of the alcohol series, differing by one CH₂ unit.
  7. Assertion (A): Aldehydes and ketones both contain the carbonyl group.
    Reason (R): In aldehydes, the carbonyl group is bonded to at least one hydrogen atom, whereas in ketones, it is bonded to two carbon atoms.
    Answer: Both A and R are true, and R is the correct explanation of A.
    Explanation: Aldehydes and ketones differ in the bonding of the carbonyl group.
  8. Assertion (A): Alkenes undergo addition reactions.
    Reason (R): Alkenes have a double bond, which allows for the addition of atoms or groups across the bond.
    Answer: Both A and R are true, and R is the correct explanation of A.
    Explanation: The double bond in alkenes enables them to undergo addition reactions.
  9. Assertion (A): Ethanoic acid reacts with ethanol to form an ester.
    Reason (R): The reaction between an alcohol and a carboxylic acid is known as esterification.
    Answer: Both A and R are true, and R is the correct explanation of A.
    Explanation: The reaction between ethanol and ethanoic acid forms an ester through esterification.
  10. Assertion (A): Soaps are made by the saponification of fats or oils.
    Reason (R): Saponification is the hydrolysis of esters in the presence of a base to form soap and glycerol.
    Answer: Both A and R are true, and R is the correct explanation of A.
    Explanation: Saponification is the process that leads to soap formation.
  11. Assertion (A): Detergents work well in hard water.
    Reason (R): Detergents do not form insoluble precipitates with calcium and magnesium ions present in hard water.
    Answer: Both A and R are true, and R is the correct explanation of A.
    Explanation: Detergents remain effective in hard water because they do not precipitate with metal ions.
  12. Assertion (A): Butane and butene are structural isomers.
    Reason (R): Isomers are compounds that have the same molecular formula but different structures.
    Answer: A is false, but R is true.
    Explanation: Butane and butene are not structural isomers because they differ in bonding (single vs. double bonds).
  13. Assertion (A): Ethanoic acid is used as a preservative in pickles.
    Reason (R): Ethanoic acid, commonly known as vinegar, inhibits the growth of bacteria due to its acidic nature.
    Answer: Both A and R are true, and R is the correct explanation of A.
    Explanation: Ethanoic acid prevents bacterial growth in pickles due to its acidic nature.
  14. Assertion (A): Carbon tetrachloride (CCl₄) is a halogenated compound.
    Reason (R): Halogenated compounds contain one or more halogen atoms attached to carbon atoms.
    Answer: Both A and R are true, and R is the correct explanation of A.
    Explanation: CCl₄ is a halogenated compound because it contains chlorine atoms attached to carbon.
  15. Assertion (A): Propanol is an alcohol with the molecular formula C₃H₈O.
    Reason (R): Alcohols are characterized by the presence of an -OH functional group.
    Answer: Both A and R are true, and R is the correct explanation of A.
    Explanation: Propanol contains an -OH group, classifying it as an alcohol.
  16. Assertion (A): Alkanes undergo substitution reactions with halogens.
    Reason (R): In a substitution reaction, one atom in a molecule is replaced by another atom.
    Answer: Both A and R are true, and R is the correct explanation of A.
    Explanation: Alkanes can undergo substitution reactions where hydrogen atoms are replaced by halogens.
  17. Assertion (A): Ethyne is more reactive than ethane.
    Reason (R): Ethyne has a triple bond, which is more reactive than the single bond in ethane.
    Answer: Both A and R are true, and R is the correct explanation of A.
    Explanation: The triple bond in ethyne makes it more reactive than ethane.
  18. Assertion (A): The IUPAC name of CH₃-CH₂-OH is ethanol.
    Reason (R): Alcohols are named with the suffix “-ol” following the alkyl group name.
    Answer: Both A and R are true, and R is the correct explanation of A.
    Explanation: The IUPAC name of CH₃-CH₂-OH is ethanol, following the nomenclature for alcohols.
  19. Assertion (A): Unsaturated hydrocarbons are less stable than saturated hydrocarbons.
    Reason (R): Unsaturated hydrocarbons have multiple bonds, which are more reactive than single bonds.
    Answer: Both A and R are true, and R is the correct explanation of A.
    Explanation: The presence of double or triple bonds in unsaturated hydrocarbons makes them less stable.
  20. Assertion (A): Soap molecules form micelles when added to water.
    Reason (R): Micelles are spherical structures that trap dirt and grease inside, allowing them to be washed away.
    Answer: Both A and R are true, and R is the correct explanation of A.
    Explanation: Soap molecules arrange into micelles that can trap grease, helping in cleaning.