2nd Year Chemistry Chapter 5 TestHALOGENOALKANES

Q1. Multiple choice questions (Attempt all · 10 × 1 = 10)

1. Which of the following is explicitly mentioned as a factor affecting reactivity alongside bond energy?

   1. Boiling point

   2. Surface area

   3. Bond polarity

   4. Molecular geometry

2. What has primarily led to restrictions or banning of DDT in developed countries?

   1. High manufacturing cost

   2. Persistence in the environment

   3. Lack of effectiveness

   4. Bad odor

3. What is the overall reaction kinetics order followed by an S_N1 mechanism?

   1. Zero order

   2. First order

   3. Second order

   4. Third order

4. What are the secondary products formed alongside ethene in the elimination reaction?

   1. H₂O and NaBr

   2. H₂ and NaBr

   3. O₂ and NaBr

   4. HBr only

5. Which halogenoalkane is the most reactive based on bond energy?

   1. R–F

   2. R–Cl

   3. R–Br

   4. R–I

6. What phosphorus-containing by-product is formed when an alcohol reacts with PCl₅?

   1. H₃PO₃

   2. POCl₃

   3. P₂O₅

   4. PH₃

7. Which compounds were historically used as refrigerants but are now replaced due to ozone depletion?

   1. Chlorofluorocarbons (CFCs)

   2. Hydrofluorocarbons (HFCs)

   3. Polyvinyl chloride (PVC)

   4. Polytetrafluoroethylene (PTFE)

8. What reagent is used alongside pyridine to prepare pure alkyl chlorides from alcohols?

   1. Thionyl chloride

   2. Phosphorus trichloride

   3. Hydrochloric acid

   4. Phosphorus pentachloride

9. What happens to the lone pair of electrons on the chlorine atom in a halogenoarene?

   1. It remains localized

   2. It is lost to the catalyst

   3. It is delocalised into the ring

   4. It forms a coordinate bond

10. The first step in the S_N1 mechanism acts as follows:

    1. Rate-determining step

    2. Ionization step

    3. Nucleophilic attack

    4. Deprotonation step