Question

The order of reactivity of various alkyl halides towards nucleophilic substitution follows the order

A. $$R - I > R - Br > R - Cl > R - F$$  
B. $$R - F > R - Cl > R - Br > R - I$$
C. $$R - Cl > R - Br > R - I > R - F$$
D. $$R - Br > R - I > R - Cl > R - F$$
Answer :   $$R - I > R - Br > R - Cl > R - F$$
Solution :
The alkyl halides are very reactive due to highly polarised $$C -X$$  bond with a large difference in electronegativities of carbon and halogen atoms. The order of reactivity is iodides > bromides > chlorides > fluorides.

Releted MCQ Question on
Organic Chemistry >> Electrophilic Aromatic Substitution (Haloalkanes and Haloarenes)

Releted Question 1

The reaction of toluene with chlorine in presence of ferric chloride gives predominantly :

A. benzoyl chloride
B. $$m $$ - chlorotoluene
C. benzyl chloride
D. $$o $$ - and $$p $$ - chlorotoluene
Releted Question 2

Bottles containing $${C_6}{H_5}I$$  and $${C_6}{H_5}C{H_2}I$$   lost their original labels. They were labelled $$A$$ and $$B$$ for testing. $$A$$ and $$B$$ were separately taken in test tubes and boiled with $$NaOH$$  solution. The end solution in each tube was made acidic with dilute $$HN{O_3}$$  and then some $$AgN{O_3}$$  solution was added. Substance B gave a yellow precipitate. Which one of the following statements is true for this experiment ?

A. $$A$$ and $${C_6}{H_5}C{H_2}I$$
B. $$B$$ and $${C_6}{H_5}I$$
C. Addition of $$HN{O_3}$$  was unnecessary
D. $$A$$ was $${C_6}{H_5}I$$
Releted Question 3

Fluorobenzene $$\left( {{C_6}{H_5}F} \right)$$  can be synthesized in the laboratory

A. by direct fluorination of benzene with $${F_2}$$  gas
B. by reacting bromobenzene with $$NaF$$  solution
C. by heating phenol with $$HF$$  and $$KF$$
D. from aniline by diazotisation followed by heating the diazonium salt with $$HB{F_4}$$
Releted Question 4

Reaction of $$trans$$  2 - phenyl - 1 - bromocyclopentane on reaction with alcoholic $$KOH$$  produces

A. 1 - phenylcyclopentene
B. 3 - phenylcyclopentene
C. 4 - phenylcyclopentene
D. 2 - phenylcyclopentene

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