100. Match A butan-1-amine, B propyne, C methyl propanoate and D propan-2-ol
with 1 alkaline hydrolysis, 2 carbylamine test, 3 ammoniacal silver nitrate, 4 Lucas reagent.
[AIPMT Mains Chemistry — 2010]
(A) A-2, B-1, C-4, D-3
(B) A-3, B-2, C-1, D-4
(C) A-2, B-3, C-1, D-4
(D) A-4, B-2, C-3, D-1
Answer: (C) A-2, B-3, C-1, D-4
Explanation: A primary amine gives the carbylamine test, and terminal propyne forms a precipitate with ammoniacal silver nitrate. The ester methyl propanoate undergoes alkaline hydrolysis, while the secondary alcohol propan-2-ol reacts with Lucas reagent with observable turbidity after a short time.
99. Arrange the acidity of I cyclohexanol, II acetic acid, III picric acid and IV phenol in decreasing order.
[AIPMT Prelims Chemistry — 2010]
(A) III > II > IV > I
(B) II > III > I > IV
(C) II > III > IV > I
(D) III > IV > II > I
Answer: (A) III > II > IV > I
Explanation: Picric acid is strongly acidic because three nitro groups stabilise its conjugate base. Acetic acid is stronger than phenol owing to carboxylate resonance stabilisation. Cyclohexanol is a much weaker acid than phenol. Therefore the descending order is picric, acetic, phenol, cyclohexanol.
98. Rank phenol I, methylphenol II, m-nitrophenol III and p-nitrophenol IV by decreasing acidity.
[AIPMT Prelims Chemistry — 2010]
(A) IV > III > I > II
(B) III > IV > I > II
(C) I > IV > III > II
(D) II > I > III > IV
Answer: (A) IV > III > I > II
Explanation: Nitro groups increase phenol acidity by withdrawing electron density; a para nitro group also offers strong resonance stabilisation of the phenoxide ion. A methyl group donates electron density and reduces acidity. Thus para-nitrophenol exceeds meta-nitrophenol, followed by phenol and methylphenol.
97. Which medicinal compound is classified as a tranquiliser?
[AIPMT Prelims Chemistry — 2010]
(A) Promethazine
(B) Valium
(C) Naproxen
(D) Mifepristone
Answer: (B) Valium
Explanation: Valium is diazepam, a benzodiazepine medicine with anxiolytic and sedative actions. Promethazine is chiefly an antihistamine, naproxen relieves pain and inflammation, and mifepristone is an antiprogestogen. Molecular structure and target-receptor binding explain why these drugs have different effects.
96. Which polymer is strengthened by pronounced intermolecular hydrogen bonding?
[AIEEE Chemistry — 2010]
(A) Teflon
(B) Nylon-6,6
(C) Polystyrene
(D) Natural rubber
Answer: (B) Nylon-6,6
Explanation: Nylon-6,6 carries polar amide groups along its chains. Carbonyl oxygen and amide hydrogen atoms of neighbouring chains form hydrogen bonds, helping give the material high tensile strength. Polystyrene, Teflon and natural rubber lack a comparably dense pattern of hydrogen-bonding amide groups.
95. Which alcohol reacts fastest with Lucas reagent, concentrated HCl and anhydrous ZnCl₂?
[AIEEE Chemistry — 2010]
(A) Butan-2-ol
(B) 2-Methylpropan-2-ol
(C) 2-Methylpropan-1-ol
(D) Butan-1-ol
Answer: (B) 2-Methylpropan-2-ol
Explanation: Tertiary alcohols such as tert-butanol react rapidly with Lucas reagent because the reaction can proceed through a relatively stable tertiary carbocation. Secondary alcohols react more slowly, and primary alcohols are typically much slower under ordinary test conditions.
94. Which symmetric alkene gives two ethanal molecules, each of mass 44 u, on reductive ozonolysis?
[AIEEE Chemistry — 2010]
(A) Propene
(B) But-1-ene
(C) But-2-ene
(D) Ethene
Answer: (C) But-2-ene
Explanation: But-2-ene has the structure CH₃CH=CHCH₃. Cleaving its central double bond yields two identical CH₃CHO molecules. Each ethanal molecule has molecular mass 44 u, satisfying both the symmetry and product-mass conditions in the question.
93. Which one of these substances is used as an explosive?
[UPSC CSE Prelims — 2009]
(A) Phosphorus trichloride
(B) Mercuric oxide
(C) Graphite
(D) Nitroglycerine
Answer: (D) Nitroglycerine
Explanation: Nitroglycerine is a highly energetic nitrate ester associated with commercial explosive applications. Graphite is a carbon allotrope, mercuric oxide is a metal oxide, and phosphorus trichloride is a reactive inorganic reagent. Of these substances, nitroglycerine is the explosive specified in the question.
92. During generation of the nitrating electrophile using HNO3 and concentrated H2SO4, how does nitric acid behave?
[AIPMT Chemistry — 2009]
(A) As an acid donating a proton
(B) As a base accepting a proton
(C) As an inert catalyst
(D) As a reducing agent
Answer: (B) As a base accepting a proton
Explanation: Concentrated sulphuric acid protonates nitric acid in the nitrating mixture. Protonated nitric acid then loses water to form the nitronium ion, NO₂⁺, which attacks an aromatic ring. Because it initially accepts a proton, nitric acid acts as a Brønsted base in this step.
91. Which of these organic drugs is employed as a tranquiliser?
[AIPMT Chemistry — 2009]
(A) Naproxen
(B) Tetracycline
(C) Chlorpheniramine
(D) Equanil
Answer: (D) Equanil
Explanation: Equanil is a brand name associated with meprobamate, a sedative and anxiolytic drug historically classified among tranquilisers. Naproxen is a non-steroidal anti-inflammatory drug, tetracycline is an antibiotic, and chlorpheniramine is an antihistamine. Their different actions arise from different pharmacological structures.
