Class 12th Chemistry Part Ii CBSE Solution
Intext Questions Pg-448- Sleeping pills are recommended by doctors to the patients suffering from sleeplessness but…
- With reference to which classification has the statement, “ranitidine is an antacid” been…
Intext Questions Pg-450Intext Questions Pg-453- Write the chemical equation for preparing sodium soap from glyceryl oleate and glyceryl…
- Following type of non-ionic detergents is present in liquid detergents, emulsifying…
Exercises- Why do we need to classify drugs in different ways?
- Explain the term, target molecules or drug targets as used in medicinal chemistry.…
- Name the macromolecules that are chosen as drug targets.
- Why should not medicines be taken without consulting doctors?
- Define the term chemotherapy.
- Which forces are involved in holding the drugs to the active site of enzymes?…
- While antacids and antiallergic drugs interfere with the function of histamines, why do…
- Low level of noradrenaline is the cause of depression. What type of drugs are needed to…
- What is meant by the term ‘broad spectrum antibiotics’? Explain.
- How do antiseptics differ from disinfectants? Give one example of each.…
- Why are cimetidine and ranitidine better antacids than sodium hydrogencarbonate or…
- Name a substance which can be used as an antiseptic as well as disinfectant.…
- What are the main constituents of dettol?
- What is tincture of iodine? What is its use?
- What are food preservatives?
- Why is the use of aspartame limited to cold foods and drinks?
- What are artificial sweetening agents? Give two examples.
- Name the sweetening agent used in the preparation of sweets for a diabetic patient.…
- What problem arises in using alitame as an artificial sweetener?
- How are synthetic detergents better than soaps?
- Explain the following terms with suitable examples (i) cationic detergents (ii) anionic…
- What are biodegradable and non-biodegradable detergents? Give one example of each.…
- Why do soaps not work in hard water?
- Can you use soaps and synthetic detergents to check the hardness of water?…
- Explain the cleansing action of soaps.
- If the water contains dissolved calcium hydrogen carbonate, out of soaps and synthetic…
- Label the hydrophilic and hydrophobic parts in the following compounds. (i) (ii) (iii)…
- Sleeping pills are recommended by doctors to the patients suffering from sleeplessness but…
- With reference to which classification has the statement, “ranitidine is an antacid” been…
- Write the chemical equation for preparing sodium soap from glyceryl oleate and glyceryl…
- Following type of non-ionic detergents is present in liquid detergents, emulsifying…
- Why do we need to classify drugs in different ways?
- Explain the term, target molecules or drug targets as used in medicinal chemistry.…
- Name the macromolecules that are chosen as drug targets.
- Why should not medicines be taken without consulting doctors?
- Define the term chemotherapy.
- Which forces are involved in holding the drugs to the active site of enzymes?…
- While antacids and antiallergic drugs interfere with the function of histamines, why do…
- Low level of noradrenaline is the cause of depression. What type of drugs are needed to…
- What is meant by the term ‘broad spectrum antibiotics’? Explain.
- How do antiseptics differ from disinfectants? Give one example of each.…
- Why are cimetidine and ranitidine better antacids than sodium hydrogencarbonate or…
- Name a substance which can be used as an antiseptic as well as disinfectant.…
- What are the main constituents of dettol?
- What is tincture of iodine? What is its use?
- What are food preservatives?
- Why is the use of aspartame limited to cold foods and drinks?
- What are artificial sweetening agents? Give two examples.
- Name the sweetening agent used in the preparation of sweets for a diabetic patient.…
- What problem arises in using alitame as an artificial sweetener?
- How are synthetic detergents better than soaps?
- Explain the following terms with suitable examples (i) cationic detergents (ii) anionic…
- What are biodegradable and non-biodegradable detergents? Give one example of each.…
- Why do soaps not work in hard water?
- Can you use soaps and synthetic detergents to check the hardness of water?…
- Explain the cleansing action of soaps.
- If the water contains dissolved calcium hydrogen carbonate, out of soaps and synthetic…
- Label the hydrophilic and hydrophobic parts in the following compounds. (i) (ii) (iii)…
Intext Questions Pg-448
Question 1.Sleeping pills are recommended by doctors to the patients suffering from sleeplessness but it is not advisable to take its doses without consultation with the doctor. Why?
Answer:Sleeping pills belong to tranquilizers class of drugs. Sleeping pills induce artificial sleep in people suffering from insomnia by depressing the activities of the central nervous system [brain and spinal cord]. When such drugs are taken for a prolonged time, such drugs can become addictive and the person can become addicted to such drugs and the aftereffects of such drugs are drowsiness, hallucinations, slow heart rate etc. and in extreme cases, the person can enter a state of coma and death can also take place.
Therefore it is highly recommended that sleeping pills should be administered to people suffering from insomnia but under the strict consultation of a doctor.
Question 2.With reference to which classification has the statement, “ranitidine is an antacid” been given?
Answer:Basically drugs can be classified in a number of ways. For example classification on basis of their chemical structure, classification on the basis of their action etc.
In the above statement, the classification is based on the pharmacological effect of drugs on the human body.
Antacids refer to those class of drugs which relieve the acidity by either reacting with the excess acid in the stomach [eg – magnesium hydroxide] or by preventing the secretion of an excess of acids by the stomach cells [eg – ranitidine].
Sleeping pills are recommended by doctors to the patients suffering from sleeplessness but it is not advisable to take its doses without consultation with the doctor. Why?
Answer:
Sleeping pills belong to tranquilizers class of drugs. Sleeping pills induce artificial sleep in people suffering from insomnia by depressing the activities of the central nervous system [brain and spinal cord]. When such drugs are taken for a prolonged time, such drugs can become addictive and the person can become addicted to such drugs and the aftereffects of such drugs are drowsiness, hallucinations, slow heart rate etc. and in extreme cases, the person can enter a state of coma and death can also take place.
Therefore it is highly recommended that sleeping pills should be administered to people suffering from insomnia but under the strict consultation of a doctor.
Question 2.
With reference to which classification has the statement, “ranitidine is an antacid” been given?
Answer:
Basically drugs can be classified in a number of ways. For example classification on basis of their chemical structure, classification on the basis of their action etc.
In the above statement, the classification is based on the pharmacological effect of drugs on the human body.
Antacids refer to those class of drugs which relieve the acidity by either reacting with the excess acid in the stomach [eg – magnesium hydroxide] or by preventing the secretion of an excess of acids by the stomach cells [eg – ranitidine].
Intext Questions Pg-450
Question 1.Why do we require artificial sweetening agents?
Answer:Diabetes mellitus is the third leading cause of death in the world. It is a medical condition in which the glucose is not consumed in the body due to inefficiency in the secretion of insulin [hormone which converts glucose to glycogen and store in liver]. Diabetes is the precursor for many other diseases like obesity, heart attacks, stroke etc. Therefore Diabetic people are advised to consume low-calorie diet [fewer carbohydrates & more proteinaceous and fiber rich]. The refined sugar like sucrose adds calorie to the diet but complex sugar and starches do not add to the calorie intake of a person and at the same time impart a sweet taste to diet. Artificial sweeteners are generally either complex sugar or protein in nature
Saccharin (500 times as sweet as sucrose), aspartame (a peptide 160 times sweeter than sucrose) are few commonly used examples of artificial sweeteners.
Why do we require artificial sweetening agents?
Answer:
Diabetes mellitus is the third leading cause of death in the world. It is a medical condition in which the glucose is not consumed in the body due to inefficiency in the secretion of insulin [hormone which converts glucose to glycogen and store in liver]. Diabetes is the precursor for many other diseases like obesity, heart attacks, stroke etc. Therefore Diabetic people are advised to consume low-calorie diet [fewer carbohydrates & more proteinaceous and fiber rich]. The refined sugar like sucrose adds calorie to the diet but complex sugar and starches do not add to the calorie intake of a person and at the same time impart a sweet taste to diet. Artificial sweeteners are generally either complex sugar or protein in nature
Saccharin (500 times as sweet as sucrose), aspartame (a peptide 160 times sweeter than sucrose) are few commonly used examples of artificial sweeteners.
Intext Questions Pg-453
Question 1.Write the chemical equation for preparing sodium soap from glyceryl oleate and glyceryl palmitate. Structural formulae of these compounds are given below.
(i) (C15H31COO)3C3H5 – Glyceryl palmitate
(ii) (C17H32COO)3C3H5 – Glyceryl oleate
Answer:Soaps are metallic salts of higher fatty acids such as palmitic acid, stearic acid, oleic acid etc. The process of saponification involves the hydrolysis of an oil or fat with an alkali (sodium hydroxide or potassium hydroxide). Oils and fats are glyceryl esters of fatty acids and may be regarded as mixed glycerides. Sodium soaps are prepared by heating the fats by sodium hydroxide.
(i) (C15H31COO)3C3H5 – Glyceryl palmitate
(ii) (C17H32COO)3C3H5 – Glyceryl oleate
Question 2.Following type of non-ionic detergents is present in liquid detergents, emulsifying agents, and wetting agents. Label the hydrophilic and hydrophobic parts in the molecule. Identify the functional group(s) present in the molecule.
Answer:The structure of the given molecule is classified as:
The functional group present in the molecule is:
1. Ether
2. Primary Alcoholic group
Alcohol group can recognize by the presence of –OH group present in the given organic compound and on the other hand, the ether group can be identified by the presence of R-O-R bonds where R represents the alkyl group present in the compound.
Write the chemical equation for preparing sodium soap from glyceryl oleate and glyceryl palmitate. Structural formulae of these compounds are given below.
(i) (C15H31COO)3C3H5 – Glyceryl palmitate
(ii) (C17H32COO)3C3H5 – Glyceryl oleate
Answer:
Soaps are metallic salts of higher fatty acids such as palmitic acid, stearic acid, oleic acid etc. The process of saponification involves the hydrolysis of an oil or fat with an alkali (sodium hydroxide or potassium hydroxide). Oils and fats are glyceryl esters of fatty acids and may be regarded as mixed glycerides. Sodium soaps are prepared by heating the fats by sodium hydroxide.
(i) (C15H31COO)3C3H5 – Glyceryl palmitate
(ii) (C17H32COO)3C3H5 – Glyceryl oleate
Question 2.
Following type of non-ionic detergents is present in liquid detergents, emulsifying agents, and wetting agents. Label the hydrophilic and hydrophobic parts in the molecule. Identify the functional group(s) present in the molecule.
Answer:
The structure of the given molecule is classified as:
The functional group present in the molecule is:
1. Ether
2. Primary Alcoholic group
Alcohol group can recognize by the presence of –OH group present in the given organic compound and on the other hand, the ether group can be identified by the presence of R-O-R bonds where R represents the alkyl group present in the compound.
Exercises
Question 1.Why do we need to classify drugs in different ways?
Answer:The basis on which drugs are classified in different ways is : - of drugs and the reasons for classification are as follows:
(i) On the basis of pharmacological effect:
This classification provides doctors the whole range of drugs available for the treatment of a particular type of problem. Hence, such a classification is very useful to doctors.
(ii) On the basis of drug action:
This classification is based on the action of a drug on a particular biochemical process.
(iii) On the basis of chemical structure:
This classification provides the range of drugs sharing common structural features and often having similar pharmacological activity.
(iv) On the basis of molecular targets:
This classification provides medicinal chemists the drugs having the same mechanism of action on targets. Hence, it is the most useful to medicinal chemists.
Question 2.Explain the term, target molecules or drug targets as used in medicinal chemistry.
Answer:In medicinal chemistry, drug targets refer to the specific key molecules involved in certain metabolic pathways that result in specific diseases. Carbohydrates, proteins, lipids, and nucleic acids are examples of drug targets.
Drugs are chemical agents designed to inhibit these target molecules by binding with the active sites of the key molecules.
Question 3.Name the macromolecules that are chosen as drug targets.
Answer:The macromolecules that are chosen as drug targets are carbohydrates, lipids, proteins, and nucleic acids.
Question 4.Why should not medicines be taken without consulting doctors?
Answer:A medicine has the tendency to bind to more than one receptor site. Thus, a medicine may be toxic for some receptor sites. Further, in most cases, medicines cause harmful effects when taken in higher doses than recommended. As a result, medicines may be poisonous in such cases. Hence, medicines should not be taken without consulting doctors.
Question 5.Define the term chemotherapy.
Answer:The use of chemicals for therapeutic effect is called chemotherapy.
For example: the use of chemicals in the diagnosis, prevention, and treatment of diseases like cancer etc.
Question 6.Which forces are involved in holding the drugs to the active site of enzymes?
Answer:Either of the following forces can be involved in holding the drugs to the active sites of enzymes: -
(i) Ionic bonding
(ii) Hydrogen bonding
(iii) Dipole − dipole interaction
(iv) Van der Waals force
Question 7.While antacids and antiallergic drugs interfere with the function of histamines, why do these not interfere with the function of each other?
Answer:Specific drugs affect only some specific or particular receptors. Antacids and anti-allergic drugs work on different receptors. This is the reason why antacids and anti-allergic drugs do not interfere with each other’s functions, but interfere with the functions of histamines.
Question 8.Low level of noradrenaline is the cause of depression. What type of drugs are needed to cure this problem? Name two drugs.
Answer:Anti-depressant drugs are needed to counteract the effect of depression. These drugs function by inhibiting the enzymes catalysing the degradation of the neurotransmitter, noradrenaline. As a result, the important neurotransmitter is slowly metabolised and then it can activate its receptor for longer periods of time.
Two anti-depressant drugs are:
(i) Iproniazid
(ii) Phenelzine
Question 9.What is meant by the term ‘broad spectrum antibiotics’? Explain.
Answer:Antibiotics that are effective against a wide range of gram-positive and gram-negative bacteria are known as broad spectrum antibiotics. Chloramphenicol is an example of a broad spectrum antibiotic. It has the following structure : -
It can be used for the treatment of typhoid, dysentery, acute fever, pneumonia, meningitis, and certain forms of urinary infections. Two other examples of broad spectrum antibiotics are vancomycin and ofloxacin. Ampicillin and amoxicillin −synthetically modified from penicillin are also broad spectrum antibiotics.
Question 10.How do antiseptics differ from disinfectants? Give one example of each.
Answer:Antiseptics and disinfectants are effective against micro-organisms. Antiseptics are applied to the living tissues such as wounds, cuts, ulcers, and diseased skin surfaces, while disinfectants are applied only to inanimate objects such as floors, drainage system, instruments, etc. Disinfectants are harmful to the living tissues. Iodine is an example of a strong antiseptic. Tincture of iodine (2 − 3 percent of solution of iodine in alcohol − water mixture) is applied to wounds. 1 percent solution of phenol is used as a disinfectant.
Question 11.Why are cimetidine and ranitidine better antacids than sodium hydrogencarbonate or magnesium or aluminium hydroxide?
Answer:Magnesium or Aluminium hydroxides do not tackle with the root cause of acidity that is they reduce the acidity by reacting with excess acid present in the stomach [neutralization reaction].
On the other hand cimetidine and ranitidine relieve acidity by preventing interaction of histamine with receptors of stomach walls and hence release of excess acid by stomach walls is stopped. So the root cause of acidity is totally eliminated.
Therefore cimetidine and ranitidine relieve the acidity by tackling the root cause whereas magnesium or aluminum hydroxide just relieves by healing only the mere cause of acidity.
Question 12.Name a substance which can be used as an antiseptic as well as disinfectant.
Answer:Phenol is one such particular substance that can act both as an antiseptic as well as a disinfectant depending upon the concentration of the solution used.
An antiseptic is used to prevent the growth of germs in cuts and wounds.
For instance, a phenol of 0.2% concentration acts as antiseptic and phenol of concentration 1% acts as a disinfectant.
Question 13.What are the main constituents of dettol?
Answer:Dettol is a well known antiseptic. It is a mixture or combination of chloroxylenol and terpineol in a suitable solvent. The structure of chloroxylenol is as follows:
The structure of terpineol is as follows:
Question 14.What is tincture of iodine? What is its use?
Answer:Iodine is a powerful antiseptic. It is employed as tincture of iodine which is an alcohol-water solution containing 2-3 percent of iodine. Iodine is widely used in healing and treatment of wounds as it kills all the microbes present in the wounded region.
Question 15.What are food preservatives?
Answer:Food preservatives are chemicals that prevent food from spoilage due to microbial growth. Table salt, sugar, vegetable oil, sodium benzoate (C6H3COONa), and salts of propanoic acids are some common examples of food preservatives.
Question 16.Why is the use of aspartame limited to cold foods and drinks?
Answer:At elevated temperatures, aspartame is unstable and break down to give a tasteless compound because of which aspartame is limited to cold foods and drinks.
Aspartame is methyl ester of the dipeptide obtained from phenylalanine and aspartic acid. It is about 180 times as sweet as cane sugar. The structure of aspartame is as follows:
Question 17.What are artificial sweetening agents? Give two examples.
Answer:Artificial sweetening agents refer to those compounds which impart sweet taste to any food product but at the same, they do not add any calories to the body.
Example: Aspartame, Alitame, Saccharin etc.
Question 18.Name the sweetening agent used in the preparation of sweets for a diabetic patient.
Answer:Artificial sweetening agents like Saccharin, Alitame, Sucrolose etc. can be used in the preparation of sweets for a diabetic patient as they do not add any calories to the body.
Diabetic people are advised to consume low-calorie diet [fewer carbohydrates & more proteinaceous and fiber rich]. The refined sugar like sucrose adds calorie to the diet but complex sugar and starches do not add to the calorie intake of a person and at the same time impart a sweet taste to diet. Artificial sweeteners are generally either complex sugar or protein in nature
Question 19.What problem arises in using alitame as an artificial sweetener?
Answer:Alitame is a high potency artificial sweetener and it is not possible to control the sweetness imparted to food by alitame. Alitame is an artificial sweetener that is 2,000 times as sweet as sugar. This sweetness is very high as compared to the natural sugar and use of such sweetener is very critical while preparing sweet dishes. The structure of alitame is as follows:
Hence problem arises when alitame is used for sweetening purposes.
Question 20.How are synthetic detergents better than soaps?
Answer:Synthetic detergents are superior cleansing agents as compared to soaps. This is due to the following reasons.
1. Detergents are soluble even in hard water. This is because of calcium and magnesium ions present in hard water form soluble salts with detergents. Hence, detergents can be used both in soft as well as in hard water. On the other hand, soaps form insoluble salts with calcium and magnesium ions and cannot be used in hard water.
2. The aqueous solutions of detergents are usually neutral. Therefore, they do not damage delicate fabrics and can be used for washing almost all types of fabrics. On the other hand, aqueous solutions of soap are alkaline and damage delicate fabrics. Therefore, soaps cannot be used for washing delicate fabrics.
Question 21.Explain the following terms with suitable examples
(i) cationic detergents
(ii) anionic detergents
(iii) non-ionic detergents
Answer:(i) cationic detergents- Cationic detergents are quaternary ammonium salts [chlorides, bromides, acetates, etc.] having long chain alkyl groups. The cationic detergents are more expensive than anionic detergents and hence they find only limited use. However, they possess germicidal properties and are used quite extensively as germicides. The examples of cationic detergents are as follows:
(ii) anionic detergents- A detergent is said to be anionic when the large part of its molecule is an anion and is involved in the cleansing action. The anionic detergents are also effective in slightly acidic solutions. In slightly acidic solutions, they form an alkyl hydrogen sulphate which is a soluble material. In contrast, soaps react with acidic solutions to form insoluble fatty acids.The examples of anionic detergents are as follows:
(iii) non-ionic detergents- These do not contain any ion in their constitution. They are the esters of high molecular mass formed by the reaction between polyethylene glycol and stearic acid. Some non-ionic detergents are used as dishwashing detergents.The example of a non-ionic detergent is as follows:
Question 22.What are biodegradable and non-biodegradable detergents? Give one example of each.
Answer:It has been found that the detergents having a great deal of branching in the hydrocarbon tail are not biodegradable and cause pollution in rivers and waterways. This is because the presence of side chains in the hydrocarbon tail stops bacteria from attacking and breaking the chains. This results in slow degradation of detergent molecules leading to their accumulation in water ways. Alkylbenzene sulphonates having branched chain alkyl groups possess poor biodegradability and cause pollution in rivers and water ways. Such detergents are termed as non-biodegradable or hard detergents.
Examples: 
The alkyl sulphates do not possess branching and are therefore biodegradable. They do not cause pollution. Alkyl benzene sulphonates in which the phenyl group is either attached to the end of a long chain alkyl group are also biodegradable and do not cause pollution. These are termed as soft detergents. Nowadays, efforts are being made to keep the amount of branching in the detergent molecule to a minimum. Since unbranched chains are more prone to attack by bacteria, the detergents having no branching or minimum branching are easily biodegraded and pollution is prevented.
Example: Sodium-4-(1,3,5,7-Tetra Methyl Octyl) Benzene Sulphonate
Question 23.Why do soaps not work in hard water?
Answer:The commonly used soaps are the sodium and potassium salts of higher fatty acids. They are soluble in water and give good lather to it. On the other hand, calcium and magnesium salts of higher fatty acids (calcium and magnesium soaps) are insoluble in water and do not produce lather. Hard water contains Ca2+and Mg2+ ions. When a sodium or potassium soap is added to hard water, it gets converted into an insoluble calcium or magnesium soap as shown ahead.
Due to the conversion of sodium or potassium soaps into calcium or magnesium soaps in the presence of hard water, the common soaps are unable to emulsify the greasy dirt and clean the dirty object. They do not produce lather with hard water. The calcium and magnesium soaps thus produced appear on the surface as insoluble sticky grey scum. This involves a waste of the common soap and the fabrics being washed get discoloured and hardened. This is why the commonly used sodium and potassium soaps can not be used as cleansing agents with hard water.
Question 24.Can you use soaps and synthetic detergents to check the hardness of water?
Answer:Soaps can be very easily used for checking the hardness of water as soap lathers with soft water and with hard water, soap is precipitated.
On the other hand, synthetic detergents are soluble in hard water and soft water. Hence it cannot be used for checking the hardness of water.
Question 25.Explain the cleansing action of soaps.
Answer:Soap molecules form micelles around an oil droplet [dirt] in such way that the hydrophobic parts of the stearate ions attach themselves to the oil droplet and the hydrophilic parts projects outside the oil droplet. Due to the polar nature of the hydrophilic parts, the stearate ions [along with the dirt]are pulled into the water, thereby removing the dirt from the cloth.
Question 26.If the water contains dissolved calcium hydrogen carbonate, out of soaps and synthetic detergents which one will you use for cleaning clothes?
Answer:If calcium salts are present in water, then it is recommended to use synthetic detergent because soap will precipitate to give white scums and it will not clean the clothes.
On the other hand, if we use synthetic detergents, it will be dissolved in hard water also and provide effective cleaning of dirty clothes.
Question 27.Label the hydrophilic and hydrophobic parts in the following compounds.
(i) 
(ii) 
(iii) CH3(CH2)16COO(CH2CH2O)nCH2CH2OH
Answer:(i) 
(ii) 
(iii) 
Alkyl groups are water hating groups that is they do not get assimilated in water easily whereas on the other hand functional groups like sulphonates, alcohol etc are water liking groups that is these groups dissolve in water easily. Therefore hydrophobic part in the above detergents is the long chain alkyl group and the hydrophilic part is the alcohol group, sulphonates group etc.
Why do we need to classify drugs in different ways?
Answer:
The basis on which drugs are classified in different ways is : - of drugs and the reasons for classification are as follows:
(i) On the basis of pharmacological effect:
This classification provides doctors the whole range of drugs available for the treatment of a particular type of problem. Hence, such a classification is very useful to doctors.
(ii) On the basis of drug action:
This classification is based on the action of a drug on a particular biochemical process.
(iii) On the basis of chemical structure:
This classification provides the range of drugs sharing common structural features and often having similar pharmacological activity.
(iv) On the basis of molecular targets:
This classification provides medicinal chemists the drugs having the same mechanism of action on targets. Hence, it is the most useful to medicinal chemists.
Question 2.
Explain the term, target molecules or drug targets as used in medicinal chemistry.
Answer:
In medicinal chemistry, drug targets refer to the specific key molecules involved in certain metabolic pathways that result in specific diseases. Carbohydrates, proteins, lipids, and nucleic acids are examples of drug targets.
Drugs are chemical agents designed to inhibit these target molecules by binding with the active sites of the key molecules.
Question 3.
Name the macromolecules that are chosen as drug targets.
Answer:
The macromolecules that are chosen as drug targets are carbohydrates, lipids, proteins, and nucleic acids.
Question 4.
Why should not medicines be taken without consulting doctors?
Answer:
A medicine has the tendency to bind to more than one receptor site. Thus, a medicine may be toxic for some receptor sites. Further, in most cases, medicines cause harmful effects when taken in higher doses than recommended. As a result, medicines may be poisonous in such cases. Hence, medicines should not be taken without consulting doctors.
Question 5.
Define the term chemotherapy.
Answer:
The use of chemicals for therapeutic effect is called chemotherapy.
For example: the use of chemicals in the diagnosis, prevention, and treatment of diseases like cancer etc.
Question 6.
Which forces are involved in holding the drugs to the active site of enzymes?
Answer:
Either of the following forces can be involved in holding the drugs to the active sites of enzymes: -
(i) Ionic bonding
(ii) Hydrogen bonding
(iii) Dipole − dipole interaction
(iv) Van der Waals force
Question 7.
While antacids and antiallergic drugs interfere with the function of histamines, why do these not interfere with the function of each other?
Answer:
Specific drugs affect only some specific or particular receptors. Antacids and anti-allergic drugs work on different receptors. This is the reason why antacids and anti-allergic drugs do not interfere with each other’s functions, but interfere with the functions of histamines.
Question 8.
Low level of noradrenaline is the cause of depression. What type of drugs are needed to cure this problem? Name two drugs.
Answer:
Anti-depressant drugs are needed to counteract the effect of depression. These drugs function by inhibiting the enzymes catalysing the degradation of the neurotransmitter, noradrenaline. As a result, the important neurotransmitter is slowly metabolised and then it can activate its receptor for longer periods of time.
Two anti-depressant drugs are:
(i) Iproniazid
(ii) Phenelzine
Question 9.
What is meant by the term ‘broad spectrum antibiotics’? Explain.
Answer:
Antibiotics that are effective against a wide range of gram-positive and gram-negative bacteria are known as broad spectrum antibiotics. Chloramphenicol is an example of a broad spectrum antibiotic. It has the following structure : -
It can be used for the treatment of typhoid, dysentery, acute fever, pneumonia, meningitis, and certain forms of urinary infections. Two other examples of broad spectrum antibiotics are vancomycin and ofloxacin. Ampicillin and amoxicillin −synthetically modified from penicillin are also broad spectrum antibiotics.
Question 10.
How do antiseptics differ from disinfectants? Give one example of each.
Answer:
Antiseptics and disinfectants are effective against micro-organisms. Antiseptics are applied to the living tissues such as wounds, cuts, ulcers, and diseased skin surfaces, while disinfectants are applied only to inanimate objects such as floors, drainage system, instruments, etc. Disinfectants are harmful to the living tissues. Iodine is an example of a strong antiseptic. Tincture of iodine (2 − 3 percent of solution of iodine in alcohol − water mixture) is applied to wounds. 1 percent solution of phenol is used as a disinfectant.
Question 11.
Why are cimetidine and ranitidine better antacids than sodium hydrogencarbonate or magnesium or aluminium hydroxide?
Answer:
Magnesium or Aluminium hydroxides do not tackle with the root cause of acidity that is they reduce the acidity by reacting with excess acid present in the stomach [neutralization reaction].
On the other hand cimetidine and ranitidine relieve acidity by preventing interaction of histamine with receptors of stomach walls and hence release of excess acid by stomach walls is stopped. So the root cause of acidity is totally eliminated.
Therefore cimetidine and ranitidine relieve the acidity by tackling the root cause whereas magnesium or aluminum hydroxide just relieves by healing only the mere cause of acidity.
Question 12.
Name a substance which can be used as an antiseptic as well as disinfectant.
Answer:
Phenol is one such particular substance that can act both as an antiseptic as well as a disinfectant depending upon the concentration of the solution used.
An antiseptic is used to prevent the growth of germs in cuts and wounds.
For instance, a phenol of 0.2% concentration acts as antiseptic and phenol of concentration 1% acts as a disinfectant.
Question 13.
What are the main constituents of dettol?
Answer:
Dettol is a well known antiseptic. It is a mixture or combination of chloroxylenol and terpineol in a suitable solvent. The structure of chloroxylenol is as follows:
The structure of terpineol is as follows:
Question 14.
What is tincture of iodine? What is its use?
Answer:
Iodine is a powerful antiseptic. It is employed as tincture of iodine which is an alcohol-water solution containing 2-3 percent of iodine. Iodine is widely used in healing and treatment of wounds as it kills all the microbes present in the wounded region.
Question 15.
What are food preservatives?
Answer:
Food preservatives are chemicals that prevent food from spoilage due to microbial growth. Table salt, sugar, vegetable oil, sodium benzoate (C6H3COONa), and salts of propanoic acids are some common examples of food preservatives.
Question 16.
Why is the use of aspartame limited to cold foods and drinks?
Answer:
At elevated temperatures, aspartame is unstable and break down to give a tasteless compound because of which aspartame is limited to cold foods and drinks.
Aspartame is methyl ester of the dipeptide obtained from phenylalanine and aspartic acid. It is about 180 times as sweet as cane sugar. The structure of aspartame is as follows:
Question 17.
What are artificial sweetening agents? Give two examples.
Answer:
Artificial sweetening agents refer to those compounds which impart sweet taste to any food product but at the same, they do not add any calories to the body.
Example: Aspartame, Alitame, Saccharin etc.
Question 18.
Name the sweetening agent used in the preparation of sweets for a diabetic patient.
Answer:
Artificial sweetening agents like Saccharin, Alitame, Sucrolose etc. can be used in the preparation of sweets for a diabetic patient as they do not add any calories to the body.
Diabetic people are advised to consume low-calorie diet [fewer carbohydrates & more proteinaceous and fiber rich]. The refined sugar like sucrose adds calorie to the diet but complex sugar and starches do not add to the calorie intake of a person and at the same time impart a sweet taste to diet. Artificial sweeteners are generally either complex sugar or protein in nature
Question 19.
What problem arises in using alitame as an artificial sweetener?
Answer:
Alitame is a high potency artificial sweetener and it is not possible to control the sweetness imparted to food by alitame. Alitame is an artificial sweetener that is 2,000 times as sweet as sugar. This sweetness is very high as compared to the natural sugar and use of such sweetener is very critical while preparing sweet dishes. The structure of alitame is as follows:
Hence problem arises when alitame is used for sweetening purposes.
Question 20.
How are synthetic detergents better than soaps?
Answer:
Synthetic detergents are superior cleansing agents as compared to soaps. This is due to the following reasons.
1. Detergents are soluble even in hard water. This is because of calcium and magnesium ions present in hard water form soluble salts with detergents. Hence, detergents can be used both in soft as well as in hard water. On the other hand, soaps form insoluble salts with calcium and magnesium ions and cannot be used in hard water.
2. The aqueous solutions of detergents are usually neutral. Therefore, they do not damage delicate fabrics and can be used for washing almost all types of fabrics. On the other hand, aqueous solutions of soap are alkaline and damage delicate fabrics. Therefore, soaps cannot be used for washing delicate fabrics.
Question 21.
Explain the following terms with suitable examples
(i) cationic detergents
(ii) anionic detergents
(iii) non-ionic detergents
Answer:
(i) cationic detergents- Cationic detergents are quaternary ammonium salts [chlorides, bromides, acetates, etc.] having long chain alkyl groups. The cationic detergents are more expensive than anionic detergents and hence they find only limited use. However, they possess germicidal properties and are used quite extensively as germicides. The examples of cationic detergents are as follows:
(ii) anionic detergents- A detergent is said to be anionic when the large part of its molecule is an anion and is involved in the cleansing action. The anionic detergents are also effective in slightly acidic solutions. In slightly acidic solutions, they form an alkyl hydrogen sulphate which is a soluble material. In contrast, soaps react with acidic solutions to form insoluble fatty acids.The examples of anionic detergents are as follows:
(iii) non-ionic detergents- These do not contain any ion in their constitution. They are the esters of high molecular mass formed by the reaction between polyethylene glycol and stearic acid. Some non-ionic detergents are used as dishwashing detergents.The example of a non-ionic detergent is as follows:
Question 22.
What are biodegradable and non-biodegradable detergents? Give one example of each.
Answer:
It has been found that the detergents having a great deal of branching in the hydrocarbon tail are not biodegradable and cause pollution in rivers and waterways. This is because the presence of side chains in the hydrocarbon tail stops bacteria from attacking and breaking the chains. This results in slow degradation of detergent molecules leading to their accumulation in water ways. Alkylbenzene sulphonates having branched chain alkyl groups possess poor biodegradability and cause pollution in rivers and water ways. Such detergents are termed as non-biodegradable or hard detergents.
Examples:
The alkyl sulphates do not possess branching and are therefore biodegradable. They do not cause pollution. Alkyl benzene sulphonates in which the phenyl group is either attached to the end of a long chain alkyl group are also biodegradable and do not cause pollution. These are termed as soft detergents. Nowadays, efforts are being made to keep the amount of branching in the detergent molecule to a minimum. Since unbranched chains are more prone to attack by bacteria, the detergents having no branching or minimum branching are easily biodegraded and pollution is prevented.
Example: Sodium-4-(1,3,5,7-Tetra Methyl Octyl) Benzene Sulphonate
Question 23.
Why do soaps not work in hard water?
Answer:
The commonly used soaps are the sodium and potassium salts of higher fatty acids. They are soluble in water and give good lather to it. On the other hand, calcium and magnesium salts of higher fatty acids (calcium and magnesium soaps) are insoluble in water and do not produce lather. Hard water contains Ca2+and Mg2+ ions. When a sodium or potassium soap is added to hard water, it gets converted into an insoluble calcium or magnesium soap as shown ahead.
Due to the conversion of sodium or potassium soaps into calcium or magnesium soaps in the presence of hard water, the common soaps are unable to emulsify the greasy dirt and clean the dirty object. They do not produce lather with hard water. The calcium and magnesium soaps thus produced appear on the surface as insoluble sticky grey scum. This involves a waste of the common soap and the fabrics being washed get discoloured and hardened. This is why the commonly used sodium and potassium soaps can not be used as cleansing agents with hard water.
Question 24.
Can you use soaps and synthetic detergents to check the hardness of water?
Answer:
Soaps can be very easily used for checking the hardness of water as soap lathers with soft water and with hard water, soap is precipitated.
On the other hand, synthetic detergents are soluble in hard water and soft water. Hence it cannot be used for checking the hardness of water.
Question 25.
Explain the cleansing action of soaps.
Answer:
Soap molecules form micelles around an oil droplet [dirt] in such way that the hydrophobic parts of the stearate ions attach themselves to the oil droplet and the hydrophilic parts projects outside the oil droplet. Due to the polar nature of the hydrophilic parts, the stearate ions [along with the dirt]are pulled into the water, thereby removing the dirt from the cloth.
Question 26.
If the water contains dissolved calcium hydrogen carbonate, out of soaps and synthetic detergents which one will you use for cleaning clothes?
Answer:
If calcium salts are present in water, then it is recommended to use synthetic detergent because soap will precipitate to give white scums and it will not clean the clothes.
On the other hand, if we use synthetic detergents, it will be dissolved in hard water also and provide effective cleaning of dirty clothes.
Question 27.
Label the hydrophilic and hydrophobic parts in the following compounds.
(i)
(ii)
(iii) CH3(CH2)16COO(CH2CH2O)nCH2CH2OH
Answer:
(i)
(ii)
(iii)
Alkyl groups are water hating groups that is they do not get assimilated in water easily whereas on the other hand functional groups like sulphonates, alcohol etc are water liking groups that is these groups dissolve in water easily. Therefore hydrophobic part in the above detergents is the long chain alkyl group and the hydrophilic part is the alcohol group, sulphonates group etc.