JEE Chemistry Chemistry In Everyday Life MCQs Set 04

Answer: (c) 4-Aminophenol (p-aminophenol)

Explanation:
1. Paracetamol is p-hydroxyacetanilide, that is 4-HO-C\(_6\)H\(_4\)-NHCOCH\(_3\).
2. Its NH-COCH\(_3\) group is obtained by acetylating the NH\(_2\) group of the para isomer.
3. So the starting compound is 4-aminophenol.

Teacher's Note:
1. Acetylation replaces an H of the amino group by COCH\(_3\).
2. The OH and amide groups in paracetamol are para to each other.

Answer: (c) Acetylsalicylic acid

Explanation:
1. Aspirin is made by acetylating the phenolic OH of salicylic acid (o-hydroxybenzoic acid) with acetic anhydride.
2. The product is 2-acetoxybenzoic acid, also called acetylsalicylic acid.

Teacher's Note:
1. Salicylic acid itself is o-hydroxybenzoic acid, not aspirin.
2. Aspirin is a non-narcotic analgesic, an antipyretic and an anti-blood-clotting agent.

Answer: (c) Aspartame

Explanation:
1. Aspartame is a dipeptide methyl ester. It breaks down at cooking temperature.
2. So it can be used only in cold foods and soft drinks.
3. Saccharin, sucralose and alitame are stable at cooking temperature.

Teacher's Note:
1. Remember the relative sweetness: aspartame 100, saccharin 550, sucralose 600, alitame 2000 times cane sugar.
2. Aspartame is the first choice for cold drinks because it is not heat stable.

Answer: (b) a and b

Explanation:
1. Salts of sorbic acid and propanoic acid, and sodium benzoate, are permitted preservatives.
2. Table salt, sugar and vegetable oils also act as preservatives.
3. Ethyl benzoate and ethyl alcohol are not used for this purpose.

Teacher's Note:
1. Sodium benzoate is used in limited quantity because the body metabolises it.
2. Preservatives stop spoilage by microbes.

Answer: (a) a and b

Explanation:
1. Barbiturates such as veronal and luminal are derivatives of barbituric acid.
2. They act on the central nervous system and induce sleep, so they are hypnotics and tranquilizers (sedatives).
3. Non-narcotic analgesics such as aspirin act without affecting the nervous system. Barbiturates do not belong to that group.

Teacher's Note:
1. Barbiturates are habit forming and should be taken only on medical advice.
2. They belong to the class of psychotherapeutic drugs.

Answer: (b) b and d

Explanation:
1. Sodium hydrogen carbonate and magnesium hydroxide (with aluminium hydroxide) are used as antacids.
2. Sodium carbonate is strongly basic and harmful to the stomach. Aluminium carbonate is not used as a drug.

Teacher's Note:
1. Metal hydroxides are preferred because they are insoluble and do not raise the pH above 7.
2. Excess sodium hydrogen carbonate can make the stomach alkaline and trigger even more acid secretion.

Answer: (a) a and b

Explanation:
1. Cimetidine and ranitidine block the H\(_2\) receptors in the stomach wall, so less acid is released.
2. Aspirin and paracetamol are analgesics and antipyretics, not antihistamines.

Teacher's Note:
1. Antihistamines compete with histamine for its receptor sites.
2. Brompheniramine and terfenadine are antihistamines used against allergy.

Answer: (a) a and d

Explanation:
1. Barbiturates act on the nervous system and calm a patient, so they are tranquilizers and neurologically active drugs.
2. They are not analgesics and not antiallergic drugs.

Teacher's Note:
1. Neurologically active drugs include tranquilizers, analgesics and antidepressants.
2. Barbituric acid itself is formed from malonic acid and urea (malonyl urea).

Answer: (b) Antiseptic

Explanation:
1. Bithional gives soap antiseptic properties, so medicated soaps contain it.

Teacher's Note:
1. Antiseptics kill or stop growth of microbes on living tissue.
2. Other antiseptics are dettol, savlon, iodine tincture and dilute boric acid.

Answer: (c) i-c, ii-d, iii-b, iv-a

Explanation:
1. (i) is an ester of stearic acid with polyethylene glycol and has no ion, so it is non-ionic (c).
2. (ii) is sodium stearate, a soap (d).
3. (iii) is sodium lauryl sulphate, with a negatively charged sulphate head, so it is anionic (b).
4. (iv) is cetyltrimethylammonium bromide with a positive nitrogen, so it is cationic (a).

Teacher's Note:
1. Anionic: sulphate or sulphonate head. Cationic: quaternary ammonium head. Non-ionic: no charge.
2. Soaps are sodium or potassium salts of long-chain fatty acids.

Answer: (c) Sucralose

Explanation:
1. Sucralose is a trichloro derivative of sucrose.
2. Aspartame and alitame are dipeptide based, and saccharin is ortho-sulphobenzimide. None of these has chlorine.

Teacher's Note:
1. Sucralose is about 600 times sweeter than cane sugar and is stable at cooking temperature.
2. It does not add calories because the body does not metabolise it.

Answer: (a) Thyroxine

Explanation:
1. Thyroxine, secreted by the thyroid gland, is an iodine-containing amino-acid derivative.
2. Insulin is a protein, testosterone is a steroid and adrenaline is an amine hormone. None contains iodine.

Teacher's Note:
1. Deficiency of iodine causes goitre.
2. Common salt is iodised to prevent this.

Answer: (b) Sucrose - Reducing sugar

Explanation:
1. Sucrose has the glycosidic bond between C-1 of glucose and C-2 of fructose, so both anomeric carbons are locked. It does not reduce Tollens' or Fehling's reagent, so it is a non-reducing sugar.
2. The other three pairs are correct.

Teacher's Note:
1. Reducing sugars have a free hemiacetal or hemiketal group, for example glucose, fructose, maltose and lactose.
2. Sucrose is called invert sugar after hydrolysis because the rotation changes sign.

Answer: (d) Essential amino acids (proteins)

Explanation:
1. Kwashiorkor is a form of malnutrition seen in children whose diet lacks protein.
2. Protein deficiency means a shortage of essential amino acids.

Teacher's Note:
1. Its symptoms include swelling of the belly and limbs and poor growth.
2. Marasmus is the related condition caused by a shortage of both protein and calories.

Answer: (b) Saponification

Explanation:
1. Heating a fat (a glyceryl ester of fatty acids) with aqueous NaOH gives glycerol and the sodium salt of the fatty acid, which is soap.
2. This alkaline hydrolysis is saponification.

Teacher's Note:
1. \( \ce{(RCOO)3C3H5 + 3NaOH -> 3RCOONa + C3H5(OH)3} \).
2. Sodium soaps are hard. Potassium soaps are soft.

Answer: (b) Coconut oil

Explanation:
1. Soap needs a fat or oil that is an ester of fatty acids and glycerol.
2. Coconut oil is such a triglyceride. Paraffin, kerosene and turpentine are hydrocarbons and do not undergo saponification.

Teacher's Note:
1. Mineral oils are mixtures of hydrocarbons, not esters.
2. Vegetable oils such as coconut, palm and olive are used in soap making.

Answer: (b) A trihydric alcohol

Explanation:
1. A fat is a triester of glycerol with long-chain fatty acids.
2. Hydrolysis gives glycerol (propane-1,2,3-triol), which has three OH groups, together with fatty acids or their salts.

Teacher's Note:
1. Glycerol is a by-product recovered in soap manufacture.
2. Dihydric means two OH groups, trihydric means three.

Answer: (b) Sodium dodecylbenzenesulphonate

Explanation:
1. ABS stands for alkyl benzene sulphonate.
2. Sodium dodecylbenzenesulphonate has a dodecyl chain on a benzene ring carrying the sulphonate group.

Teacher's Note:
1. Branched-chain ABS detergents are not biodegradable and cause foam in rivers.
2. Straight-chain LAS detergents are biodegradable.

Answer: (c) Ampicillin and amoxycillin are natural antibiotics

Explanation:
1. Ampicillin and amoxycillin are semi-synthetic modifications of penicillin, so they are not natural antibiotics.
2. The other statements are true: 0.2 percent phenol is an antiseptic while 1 percent phenol is a disinfectant, sulpha drugs are synthetic, and aspirin reduces pain and fever.

Teacher's Note:
1. Penicillin G is a natural antibiotic.
2. Semi-synthetic means a natural product that is chemically modified.

Answer: (d) Tranquillisers

Explanation:
1. Barbituric acid is formed from malonic acid and urea.
2. Its derivatives such as veronal, luminal and seconal are sedatives and hypnotics, which are tranquillisers.

Teacher's Note:
1. Barbiturates are a major group of tranquillisers.
2. Their use is restricted because they can cause dependence.

Answer: (d) Chloramphenicol

Explanation:
1. Chloramphenicol is a broad spectrum antibiotic used against typhoid, dysentery, acute fever, certain urinary infections and meningitis.
2. Penicillin works mainly on gram positive bacteria, bithional is an antiseptic, and norethindrone is a birth control drug.

Teacher's Note:
1. Chloramphenicol is one of the few antibiotics that can be taken by mouth in a high dose for typhoid.
2. Broad spectrum antibiotics act on both gram positive and gram negative bacteria.

Answer: (c) Chloroxylenol and terpineol

Explanation:
1. Dettol is a mixture of chloroxylenol and terpineol.
2. Its dilute solution is used as an antiseptic for cleaning wounds.

Teacher's Note:
1. Chloroxylenol is 4-chloro-3,5-dimethylphenol.
2. Do not confuse it with xylenol, which has no chlorine.

Answer: (d) Bithional is used as an antifertility drug

Explanation:
1. Bithional is an antiseptic added to soaps. It is not an antifertility drug.
2. Norethindrone is an example of an antifertility (birth control) drug.
3. The other three statements are correct.

Teacher's Note:
1. Antifertility drugs are synthetic estrogen-progesterone derivatives.
2. Bithional gives medicated soaps their antiseptic action.

Answer: (c) Prostaglandins

Explanation:
1. Prostaglandins are produced in the tissues during injury. They stimulate inflammation and sensitise pain receptors.
2. Aspirin inhibits the enzyme that makes prostaglandins, so it relieves pain and fever.

Teacher's Note:
1. Histamine is mainly responsible for allergy symptoms and gastric acid secretion.
2. This is why aspirin is a non-narcotic analgesic and antipyretic.

Answer: (d) Soframycin is used as a disinfectant

Explanation:
1. Soframycin (framycetin) is an antibiotic skin ointment applied to wounds. It is not a disinfectant.
2. Disinfectants are used on floors and instruments, not applied on living tissue.
3. The other statements are correct.

Teacher's Note:
1. Disinfectants are toxic to living tissue, so they cannot be used on the body.
2. Antiseptics and antibiotics can be applied to living tissue.