Chapter 9 Aromatic Hydrocarbons

2nd year chemistry chapter 8 importnat MCQs

Choices written in red are correct answers.

1.   The – CH₃ group is:

(a)    Ortho directing only         (b)  Meta directing only

        (c)  Para directing only               (d)  Both ortho and para directing

2.   Toluene undergoes oxidation with hot acidic KMnO₄ to form:

(a)    Benzoic acid    (b)  Benzyl alcohol      

(c)  Benzyl chloride (d)  Benazldehycle

3.   Benzene reacts with chlorine in the presence of FeCl₃ to form: 

(a)    m – dichlorobenzene (b)  Chlorobenzene  (c)  Benzyl chloricle  (d)  Hexachlorobenzene 

4.   The – COOH group in benzoic acid is:

(a)    Both ortho & para directing      (b)  Ortho directing only

        (c)  Meta directing only                      (d)  Para directing only

5.   Bakelite is obtained from phenol by reacting with:

(a)    Acetaldehyde         (b)  Acetal          

        (c)  Formaldehyde             (d) Chlorobenzene

6.   Which of the following generally have low carbon to hydrogen ratio

(a)    Alkane            (b)  Aromatic hydrocarbons         

        (c)  Alkene               (d)  Alkyne

7.   Nitration Of Benzene is a

(a)    Nucleophilic substitution reaction (b) Electrophilic substitution reaction (c)   Electrophilic addition  (d) Nucleophilic ad-

dition reaction

8.   The carbon atoms in benzene are:

(a)    Sp³ hybridized    (b) Sp² hybridized    

(c)  Sp hybridized      (d)  Non of them 9. The total no. of sigma bonds in benzene are:

        (a) 6                 (b) 12                       (c) 18                       (d) 3

10.               The pi () molecular orbital in benzene contains

(a)        2 electrons    (b)  4 es            (c)  6 es            (d)  3 es

11.               The C – C bond angles in benzene are

(a)        120^o                    (b)  90^o                               (c)  109.2          (d) 180^o

12.               Two adjacent substituents on benzene ring is said to be (a)  Ortho to one another   (b)  Meta to one another

        (c)  Para to one another                     (d)  None of the above

13.               Benzene reacts with a mixture of conc. HNO₃ + H₂SO₄ to form:

(a)        Phenol         (b)  Benzene sulphonic acid        

        (c)  Nitrobenzene      (d)  Toluene

14.               Aromatic hydrocarbons are also called

(a)        Benzene               (b)    Arenes               

        (c)    Cyclic compound       (d)    None of the above

15.               The attacking species in aromatic substitution reaction is:

(a)    a nucleophile           (b)  An electrophile     

        (c)  a free – radical            (d)  None of the above

16.               Benzene reacts with methyl chloride in the presence of AlCl₃ to form:

(a)    Toluene                 (b)  Chloro benzene 

(c)  n – dichloro benzene  (d)  Nitrobenzene

17.               What happens when phenol is distilled with Zn dust:

(a)    Benzene is formed                 (b)  Toluene is formed                

        (c)  Acetylene is formed                     (d)  None of the above

18.               Which does not have a carboxyl group?

(a)    Benzoic acid            (b)  Ethanoic acid       

        (c)  Picric acid                   (d)  Methanoic acid

19.               Grignard reagent is reactive due to

(a)    The presence of halogen atom                 (b)    The presence of Mg atom

        (c)   The polarity of C – Mg bond        (d)    None of the above

20.               The active species involved in nitration of benzene is 

(a)    NO+                        (b)  NO2                  (c)  NO2+    (d)  NO3-1 

21.               Benzophenone is called

(a)    Diphenylketone                (b)  Diethyl ketone

        (c)  Methyl phenyl ketone           (d)  Biphenyl

22.               Benzene normally shows __________ reactions

(a)    Addition         (b)  Substitution

        (c)  Limiting                               (d)  Elimination

23.               Which is called soda lime

(a)    NaOH             (b)  CaO

        (c)  NaOH + CaO                      (d)  Na₂CO₃   

24.               The conversion of n – hexane into benzene by heating in the presence of pt is called

(a)    Isomerization         (b)  Aromatization (c)  Dealkylation             (d)  Rearrangement