1
MCQ (Single Correct Answer)

AIPMT 2010 Mains

When glycerol is treated with excess of HI, it produces
A
2-iodopropane
B
allyl iodide
C
propene
D
glycerol triiodide

Explanation

Glycerol when treated with excess HI produces 2–iodopropane.

2
MCQ (Single Correct Answer)

AIPMT 2010 Mains

Following compounds are given


Which of the above compound(s), on being warmed with iodine solution and NaOH, will give iodoform?
A
(i), (iii) and (iv)
B
Only (ii)
C
(i), (ii) and (iii)
D
(i) and (ii)

Explanation

The iodoform test is exhibited by ethyl alcohol, acetaldehyde, acetone, methyl ketones, those alcohols which possess
CH3CH(OH)— group, acetophenone, $$\alpha $$-hydroxypropionic acid, keto acid, 2-aminoalkanes, etc.
3
MCQ (Single Correct Answer)

AIPMT 2010 Prelims

Among the following four compounds
(i)  Phenol
(ii)  Methyl phenol
(iii)  Meta-nitrophenol
(iv)  Para-nitrophenol

The acidity order is
A
(iv) > (iii) > (i) > (ii)
B
(iii) > (iv) > (i) > (ii)
C
(i) > (iv) > (iii) > (ii)
D
(ii) > (i) > (iii) > (iv)

Explanation

In phenols, the presence of electron releasing groups decrease the acidity, whereas presence of electron withdrawing groups increase the acidity, compared to phenol.

Among the meta and para-nitrophenols, the latter is more acidic as the presence of –NO2 group at para position stabilises the phenoxide ion to a greater extent than when it is present at meta position. Thus, correct order of acidity is :

(iv) > (iii) > (i) > (ii)
4
MCQ (Single Correct Answer)

AIPMT 2010 Prelims

Given are cyclohexanol (I), acetic acid (II), 2, 4, 6-trinitrophenol (III) and phenol (IV). In these the order of decreasing acidic character will be
A
III > II > IV > I
B
II > III > I > IV
C
II > III > IV > I
D
III > IV > II > I

Explanation

As we know that phenols and carboxylic acids are more acidic than aliphatic alcohols thus cyclohexanol is least acidic.

On the other hand III is more acidic than IV because of the presence of three highly electron with drawing NO2 groups on the benzene ring which makes the OH bond extremely polarized. This facilitates the release of H+.

In acetic acid the electron withdrawing $$ - \mathop C\limits_| = O$$

group polarizes the O-H bond and increases the acid strength.

Thus, acetic acid is more acidic than phenol or cyclohexanol.

Thus, the order of acidic strength will be

III > II > IV > I

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