Solutions
Question 1. Choose correct option
(A) Oxidative Rancidity is reaction
(a) addition
(b) subtitution
(c) Free radical
(d) combination
(c) Free radical
(B) Saponification is carried out by
(a) oxidation
(b) alkaline hydrolysis
(c) polymarisation
(d) Free radical formation
(b) alkaline hydrolysis
Explanation: Saponification is the process of converting fats or oils (triglycerides) into soap and glycerol through the reaction with a strong alkali, such as sodium hydroxide (NaOH) or potassium hydroxide (KOH). This reaction involves the alkaline hydrolysis of the ester bonds in triglycerides.
(C) Aspirin is chemically named as
(a) Salicylic acid
(b) acetyl salicylic acid
(c) chloroxylenol
(d) thymol
(b) acetyl salicylic acid
(D) Find odd one out from the following
(a) dettol
(b) chloroxylenol
(c) paracetamol
(d) trichlorophenol
(c) paracetamol
Explanation:
- Dettol, chloroxylenol, and trichlorophenol are antiseptics or disinfectants used for killing germs and preventing infections.
- Paracetamol, on the other hand, is a medication used as an analgesic (pain reliever) and antipyretic (fever reducer), not an antiseptic.
Hence, paracetamol is the odd one out.
(E) Arsenic based antibiotic is
(a) Azodye
(b) prontosil
(c) salvarsan
(d) sulphapyridine
(c) salvarsan
(F) The chemical used to slow down the browning action of cut fruit is
(a) SO3
(b) SO2
(c) H2SO4
(d) Na2CO3
(b) SO₂ (Sulfur dioxide).
Explanation: Sulfur dioxide is commonly used to prevent the browning of cut fruits by inhibiting the action of enzymes responsible for oxidation. This chemical is often employed in the food industry for preserving the appearance of fresh produce.
(G) The chemical is responsible for the rancid flavour of fats is
(a) Butyric acid
(b) Glycerol
(c) Protein
(d) Saturated fat
(b) Glycerol
(H) Health benefits are obtained by consumption of
(a) Saturated fats
(b) trans fats
(c) mono unsaturated fats
(d) all of these
(c) mono unsaturated fats
Explanation : Consuming monounsaturated fats (MUFAs) can provide several health benefits due to their positive impact on the body's metabolism and overall health.
MUFAs help reduce bad cholesterol levels (LDL). MUFAs improve insulin sensitivity, which is beneficial for blood sugar control.
Question 2. Explain the following :
(A) Cooking makes food easy to digest.
- The uncooked food mixture is a heterogeneous suspension which becomes a colloidal matter on cooking.
- During the cooking process, high polymers of carbohydrates or proteins are hydrolyzed to smaller polymeric units.
- As a result, the constituent nutrient molecules present in cooked food are smaller in size and hence, easier to digest, than the uncooked food.
Hence, cooking makes food easy to digest.
(B) On cutting some fruits and vegetable turn brown.
Cutting of fruits and vegetables damages the cells, resulting in the release of chemicals. Depending on the pH of fruits/vegetables, polyphenols are released. Due to the action of an enzyme, these polyphenols react with oxygen present in the air and get oxidized to form quinones.
Quinones further undergo reactions including polymerization, which results in the formation of brown coloured products called tannins. Thus, on cutting, some fruits and vegetables turn brown.
(C) Vitamin E is added to packed edible oil.
Vitamin E (tocophenol), a natural antioxidant, is added to packed edible oil due to its phenolic−OH group structure and fat−soluble long chain of saturated carbon atoms. This addition prevents oxidative rancidity in the oil, making it a valuable addition to any food product.
(D) Browning of cut apple can be prolonged by applying lemon juice.
Browning of cut apple is due to the coating of tannin. This browning process can be prolonged using reducing agent such as ascorbic acid (vitamic C) or by change of pH by adding edible acid such as lemon juice (citric acid).
(E) A diluted solution (4.8 % w/v) of 2,4,6−trichlorophenol is employed as antiseptic.
Antiseptics are used to apply on wound, cuts, ulcers, diseased skin surfaces.
The popular dettol contains most common phenol derivatives like a diluted solution (4.8% w /v) chloroxylenol and terpineol. It serves as a powerful antiseptic.
(F) Turmeric powder can be used as antiseptic.
Curcumin, the key element in turmeric, a native Indian plant, has been used for millennia to treat wounds. Turmeric powder can therefore be used as an antibacterial.
Question 3. Identify the functional groups in the following molecule :
(A) Aspirin
(B) Paracetamol
(C) Penicillin
(D) Chloramphenicol
−CO−NH− amide
− OH hydroxyl
−NO2 nitro
(E) Sulphanilamide
SO2NH2 Sulphonamide
−NH2 amine
(F) Glycerin
−OH hydroxyl (glycerol)
Question 4. Give two differences between the following
(A) Disinfectant and antiseptic
| Disinfectant | Antiseptic |
| Disinfectants are non−selective antimicrobials, which kill a wide range of micro−organisms including bacteria. | Antiseptics are applied to the living tissues to kill the bacteria. |
| Disinfectants are applied to non−living objects to kill micro−organisms. They are used in public health sanitation floors, to sterilize instruments. | Antiseptics are used to sterilise surfaces of living tissue, thus preventing its infection. |
| Example : Phenol. | Examples : Dettol, tincture iodine. |
(B) Soap and synthetic detergent
| Soap | Synthetic detergent |
| Soaps are sodium or potassium salts of long chain fatty acids which contain more than twelve carbon atoms. | Synthetic detergents containing either sodium salts of alkyl hydrogen sulphates or sodium salts of long chain alkyl benzene sulphonic acids. |
| Soaps can be broadly classified into two types, i.e., toilet soaps (prepared using KOH) and laundry soaps (prepared using NaOH). | Synthetic detergents are of three types, i.e., anionic, cationic and nonionic detergents. |
| Soaps cannot be used in hard water. | Synthetic detergents can be used in soft water as well as in hard water. |
| Potassium soaps are used in shampoo, shaving cream and bathing soaps (liquid or cake). | Anionic detergent is used in tooth paste and in the house hold work. Cationic are used as germicides. Nonionic detergents are used for washing vessels. |
(C) Saturated and unsaturated fats
| Saturated fats | Unsaturated fats |
| In saturated fat, long chains of tetrahedral carbon atoms in the fatty acid get closely packed together. | In unsaturated fats, the presence of one or more C = C bond in long chains of fatty acids, prevent molecules from packing closely together. |
| In saturated fats, the van der Waals forces between long saturated chains are strong. | In unsaturated fats, the van der Waals forces between long unsaturated chains are weak. |
| Saturated fats are solids at room temperature. The melting points of saturated fats are higher.
Examples : Coconut fat / oil butter, vanaspati ghee. |
Unsaturated fats are liquids at room temperature. Their melting points are
lower. Examples : Peanut oil, sunflower oil, soyabean oil. |
(D) Rice flour and cooked rice
| Rice flour | Cooked rice |
| Rice flour can be stored for a long period of time. It has a long shelf life. | Cooked rice cannot be stored for a longer period of time. It has a very short shelf life. |
| Rice flour is uncooked food and hence, it is difficult to digest | Cooked rice is easier to digest. |
| Rice flour contains total fat, saturated fat and monounsaturated fat. It contains potassium, calcium, iron vit B6 and magnesium | Cooked rice is very low in saturated fat cholesterol and sodium. It is a good source of manganese. |
| More calories : 366 calories/100gm | Less calories : 144 calories/100gm |
Question 5. Match the pairs.
| A group | B group |
| (A) Paracetamol | (a) Antibiotic |
| (B) Chloramphenicol | (b) Synthetic detergent |
| (C) BHT | (c) Soap |
| (D) Sodium stearate | (d) Antioxidant |
| (e) Analgesic |
(A) Paracetamol - Analgesic
(B) Chloramphenicol - Antibiotic
(C) BHT - Antioxidant
(D) Sodium stearate - Soap
Question 6. Name two drugs which reduce body pain.
The two drugs which reduce body pain are :
- aspirin (acetyl salicylic acid)
- paracetamol
Question 7. Explain with examples
(A) Antiseptics
Drugs which are applied to the living tissues to kill the bacteria and to stop their growth, thus preventing its infection are called antiseptics.
Examples :
- Iodine is a powerful antiseptic. Its 2−3 per cent solution in alcohol−water is known as tincture of iodine.
- Iodoform is also used as an antiseptic for wounds.
- A dilute aqueous solution of boric acid is a weak antiseptic used for eyes.
- Thymol obtained from oil of thyme is an excellent non toxic antiseptic.
(B) Disinfectant
- Disinfectants are non−selective antimicrobials. 2. They kill a wide range of microorganisms including bacteria.
- They are used on non−living surfaces, for example, floors, instruments, sanitary ware, etc.
- Various phenols can be used as disinfectants.
- Examples : p−Chloro−o−benzyl phenol, sulphur dioxide, chlorine, etc.
(C) Cationic detergents
Cationic detergents are quaternary ammonium salts of long chain alkyl group and a positive charge on nitrogen atom. They are used as germicides, cetyltrimethyl ammonium chloride is used in hair conditioners.
Examples :
- n−hexadecyl trimethyl ammonium chloride
- CH3(CH2)15N + (CH3)3Br − n−hexadecyl trimethyl ammonium bromide.
(D) Anionic detergents
Anionic detergents are sodium salts of long−chain alkyl sulphonic acids or long−chain alkyl−substituted benzene sulphonic acids.
Examples : Sodium lauryl sulphate: CH3(CH2)10CH2OSO3−Na+
(E) Non−ionic detergents
Nonionic detergents are ethers of polyethylene glycol with alkyl phenol or esters of polyethylene glycol with long−chain fatty acid.
Examples :
(i) Nonionic detergent containing ether linkage:
(ii) Nonionic detergent containing ester linkage:
CH3(CH2)16−COO(CH2CH2O)nCH2CH2OH
Question 8. Explain : mechanism of cleansing Action of soap with flow chart.
Mechanism of cleansing action :
Dirt is held on surfaces by oily matter, making it difficult to be washed with water. Soaps and detergents effectively clean greasy surfaces using polar head molecules and nonpolar tail carbon chains.
When soap is added to an oily part of cloth or vessel, the nonpolar chain of carbon part of soap dissolves in oil and ionic end of soap dissolves in water. The soap molecules form micelles where one of the molecules is towards the oil droplet while ionic end faces out side. This results in an emulsion in water. The soap micelle assist in dissolving the dirt in water, thus, we can wash our clothes.
Question 9. What is meant by broad spectrum antibiotic and narrow spectrum antibiotics?
Broad spectrum antibiotics : Those antibiotics which are effective against a wide range of gram positive and gram negative bacteria are known as broad spectrum antibiotics. Examples : Chloramphenicol, amoxicillin.
Broad spectrum antibiotics also kill the useful bacteria in the alimentary canal, that is their major disadvantage.
Narrow spectrum antibiotics : Those antibiotics which are effective against either gram positive or gram negative bacteria are known as narrow spectrum antibiotics.
Example : penicillin.
Question 10. Answer in one sentence
(A) Name the painkiller obtained from acetylation of salicylic acid.
The painkiller obtained from acetylation of salicylic acid is aspirin (acetyl salicylic acid).
(B) Name the class of drug often called as painkiller.
The painkiller are classified as analgesic.
(C) Who discovered penicillin?
Penicillin was discovered by Alexander Fleming. In 1929, Alexander Fleming discovered the antibacterial properties of a penicillium fungus.
(D) Draw the structure of chloroxylenol and salvarsan.
(E) Write molecular formula of Butylated hydroxy toluene.
The molecular formula of butylated hydroxy toluene is C15H24O.
(F) What is the tincture of iodine ?
2 to 3% solution of iodine in alcohol and water is called tincture of iodine.
(G) Draw the structure of BHT.
2, 6−Di−tert.butyl−p−cresol
(I) Write a chemical equation for saponification.
Saponification : Soaps are obtained by alkaline hydrolysis of natural oils and fats with NaOH or KOH. This is called saponification reaction.
Chemical Reactions : Soap and glycerol are separated by adding sodium chloride. Soap precipitates out due to common ion effect, and glycerol remains in the solution can be recovered by fractional distillation.
(J) Write the molecular formula and name of
The molecular formula : C9H8O4
Name : Acetyl salicylic acid (Aspirin) Or 2−Acetoxybenzoic acid
Question 11. Answer the following
(A) Write two examples of the following.
(a) Analgesics
(c) Antiseptics
(d) Antibiotics
(e) Disinfectant
(a) Analgesics : (i) Aspirin, (ii) paracetamol
(c) Antiseptics : (i) Dettol, (ii) thymol
(d) Antibiotics : (i) Penicillin, (ii) sulphapyridine
(e) Disinfectant : (i) Phenol, (ii) p−Chloro−o−benzyl phenol
(B) What do you understand by antioxidant ?
- An antioxidant is a substance that delays the onset of oxidant or slows down the rate of oxidation of foodstuff. It is used to extend the shelf life of food.
- Antioxidants react with oxygen−containing free radicals and thereby prevent oxidative rancidity.
- For example, BHT i.e., 3, 5−di−tert−butyl−4 hydroxy toluene, Vitamin E.