اردو

Home / Practice / Class 12 / Chemistry / Hydrocarbons

Hydrocarbons

Written by Dr. Ayesha Nadeem (Chemistry)

8 Class 12 Chemistry questions with answers and explanations.

Printable worksheet with answer key

All questions with answers
  1. Benzene has the formula:

    • 1 C6H6
    • 2 C5H5
    • 3 C6H14
    • 4 C6H12
    Show answer

    Correct answer: C6H6

    Benzene is C6H6.

    Report a mistake

  2. Alkenes mainly undergo:

    • 1 No reactions
    • 2 Elimination only
    • 3 Substitution reactions only
    • 4 Addition reactions
    Show answer

    Correct answer: Addition reactions

    The double bond opens to add atoms.

    Report a mistake

  3. The hybridisation of carbon in ethene is:

    • 1 sp2
    • 2 sp
    • 3 sp3d
    • 4 sp3
    Show answer

    Correct answer: sp2

    Each carbon in ethene forms three sigma bonds, so sp2.

    Report a mistake

  4. Addition of HBr to propene follows Markovnikov's rule to give mainly:

    • 1 Bromopropene
    • 2 1-bromopropane
    • 3 2-bromopropane
    • 4 Propane
    Show answer

    Correct answer: 2-bromopropane

    Hydrogen adds to the carbon with more hydrogens, so bromine goes on the middle carbon.

    Report a mistake

  5. Benzene reacts mainly by:

    • 1 Nucleophilic addition
    • 2 Addition
    • 3 Free radical chain only
    • 4 Electrophilic substitution
    Show answer

    Correct answer: Electrophilic substitution

    The stable ring is kept and a hydrogen is replaced.

    Report a mistake

  6. The compound CH3CH=CH2 is:

    • 1 Butene
    • 2 Propyne
    • 3 Propene
    • 4 Propane
    Show answer

    Correct answer: Propene

    It has three carbons and a double bond.

    Report a mistake

  7. The test that distinguishes alkenes from alkanes is:

    • 1 Fehling's solution
    • 2 Bromine water
    • 3 Tollens' reagent
    • 4 Litmus
    Show answer

    Correct answer: Bromine water

    Alkenes decolourise bromine water.

    Report a mistake

  8. Ethyne is also known as:

    • 1 Acetylene
    • 2 Ethylene
    • 3 Methane
    • 4 Benzene
    Show answer

    Correct answer: Acetylene

    Acetylene is the common name.

    Report a mistake

More Chemistry topics