Hydrocarbons

Written by Dr. Ayesha Nadeem (Chemistry)

Class 12 · Chemistry · 8 questions

Name: ____________________ Date: ____________

Benzene has the formula:
- A C6H6
- B C5H5
- C C6H14
- D C6H12
Alkenes mainly undergo:
- A No reactions
- B Elimination only
- C Substitution reactions only
- D Addition reactions
The hybridisation of carbon in ethene is:
- A sp2
- B sp
- C sp3d
- D sp3
Addition of HBr to propene follows Markovnikov's rule to give mainly:
- A Bromopropene
- B 1-bromopropane
- C 2-bromopropane
- D Propane
Benzene reacts mainly by:
- A Nucleophilic addition
- B Addition
- C Free radical chain only
- D Electrophilic substitution
The compound CH3CH=CH2 is:
- A Butene
- B Propyne
- C Propene
- D Propane
The test that distinguishes alkenes from alkanes is:
- A Fehling's solution
- B Bromine water
- C Tollens' reagent
- D Litmus
Ethyne is also known as:
- A Acetylene
- B Ethylene
- C Methane
- D Benzene

Answer key

1. A, 2. D, 3. A, 4. C, 5. D, 6. C, 7. B, 8. A

Benzene is C6H6.
The double bond opens to add atoms.
Each carbon in ethene forms three sigma bonds, so sp2.
Hydrogen adds to the carbon with more hydrogens, so bromine goes on the middle carbon.
The stable ring is kept and a hydrogen is replaced.
It has three carbons and a double bond.
Alkenes decolourise bromine water.
Acetylene is the common name.