Bihar Board - Class 12 Chemistry -Chapter 16: Chemistry in Everyday Life Long Answer Question

The long question answers for Chapter 16: Chemistry in Everyday Life of Class 12 Chemistry are provided here in English. These questions are based on the NCERT curriculum for Class 12. They are designed to help students develop a comprehensive understanding of the important concepts covered in the chapter. These long question answers will be beneficial not only for the Class 12 board exams but also for entrance exams like NEET. The questions and answers for Bihar Board Class 12 Chemistry, Chapter 16: Chemistry in Everyday Life, have been prepared by expert teachers at Vidyakul.

                                  Long Question Answer 

Question. 1. With the help of an example, explain how the following type of drugs function ?

(i) Analgesics
(ii) Antacids
(iii) Antifertility drugs.

Answer: (i) Analgesics : These are the chemical substances which are used for relieving pains in the body. Analgesics are of two types.

(a) Non narcotic (non-addictive drugs).
(b) Narcotic drugs.

(a) Non-narcotic (non-addictive) analgesics : Aspirin and paracetamol belong to the class of non narcotic analgesics. Aspirin is the most familiar example.

(b) Narcotic analgesics such as morphine and many of its homologues, when administered in medicinal doses, relieve pain and produce sleep.

(ii) Antacids : They are the chemical substances which can reduce or neutralize acidity. The function of the antacids is to neutralize the acidity and raise the pH level. They may also act as buffers i.e., they may now allow the pH level to fall when extra acids are released. The commonly used antacids contain magnesium salts (magnesium trisilicate) and aluminum salts (aluminum hydroxide and aluminum silicate).

(iii) Antifertility drugs : The anti-fertility drugs are mostly hormonal contraceptives. The mechanism of action of a combined oral pill is to prevent the pituitary secretion of gonadotropin hormone which is necessary for the ovulation to occur.

Progestogen-only preparations render the cervical mucus thick and scanty and thereby inhibit sperm penetration. They also inhibit tubal motility and delay the transport which is necessary for the ovulation to occur.

Question.2. Give the structure of one broad spectrum by an antibiotic. Mention two diseases for which this antibiotic can be used.

Answer: The full range of microorganisms attacked by an antibiotic is called its spectrum. Tetracycline, chloramphenicol are broad spectrum antibiotics.

Structure of chloramphenicol :

It can be used for curing :

(i) Typhoid
(ii) Dysentery
(iii) Acute fever
(iv) Certain forms of urinary infections
(v) Pneumonia
(vi) Meningitis.

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Question. 3. Define the following and give one example of each:

(i) Antihistamines
(ii) Disinfectants
(iii) antipyretics.

Answer: (i) Antihistamines : It is the group of drugs which counteract the effect of histamine in the body. These are also called anti-allergic drugs. Allergic reactions are caused due to liberation histamine in the body that is why these drugs are called antihistamines. These are used to treat allergy e.g., skin rashes, conjunctivitis and rhinitis (inflammation of nasal mucosa). Commonly drugs of this group are : diphenhydramine, chlorpheniramine, promethazine etc. Some other commonly used antihistamines are : trimeton and benadryl etc.

(ii) Disinfectants : Disinfectants kill microorganisms, but are not safe for living tissues. These are applied for inanimate objects such as floors, drainage system, instruments etc. 

Example : one percent solution of phenol, chlorine in concentration of 0.2 to 0.4 parts per million etc.

(iii) Antipyretics : The chemical substances which are used to lower the temperature of the body in high fever are called antipyretics. 

Example : Aspirin, paracetamol and phenacetin.

Question. 4. What are narcotics ?

Answer: Narcotics : Narcotics are compounds which possess general depressant action on the central nervous system. They can be classified into sedatives, hypnotics or tranquilizers and general anesthetics :

(i) Sedatives : They cause a milder form of depression. The most widely used sedatives are the bromides and the bromo-compounds. KBr is the most commonly used bromide. Bruno valetone and velero bromine are used as sedatives.

(ii) Tranquilizers : These are the compounds that help in reducing anxiety by acting on the nervous system. These induce sleep and can be habit forming. 

Examples as luminal, equanil, seconal etc.

(iii) Anaesthetics : These are the compounds used to produce unconsciousness and muscular relaxation, sufficient to allow the performance of surgical operations. Examples are ethylene, Divinyl ether and cyclopropane.

Sometimes for small operations and tooth extraction the limited area made sense either by injecting or by local application of the drugs which are called local anesthetics. 

Examples are cocaine, novocaine and lidocaine.

Question. 5. Explain the cleansing action of soaps.

Answer: All the soaps and detergents contain two characteristic groups, i.e., a water soluble (hydrophilic) group and oil-soluble (Lyophilic or lipophilic group). As a result one end of the molecule of a soap or detergent tends to go into oil phase and the other end tends to go into water phase with the net result that the material (soap or detergent) concentrates at the surface of the solution or interface.

The dirt is generally held to a dirty surface by a thin film of an oil or grease. When it is treated with soap solution, the nonpolar hydrocarbon chain of soap or detergent dissolves in oil or grease and the carboxylate part of the soap or the sulfonate group of the detergent is held by surrounding water (in fig. below). This lowers the surface tension between water and grease. As a result, a stable emulsion of oil in water is formed. When the surface or the cloth is mechanically scrubbed the loosened dirt particles are absorbed by colloidal soap particles and ultimately washed away by water.

Question. 6. What are detergents ? Give their scheme of classification. Explain. Why are detergents preferred over soaps ?

Answer: Detergents : As a result of high dissolving power, the naturally occurring water always contains dissolved materials, particularly ionic substances. Hard water contains certain metal ions, such as Ca2+ and Mg2+ . These ions react with soap, (sodium salts of stearic and similar organic acids), to produce a curdy precipitate of calcium and magnesium salts. This precipitate adheres to clothing and blocks the ability of soaps to remove oil and grease from fabrics. Synthetic detergents are very similar to the salts of fatty acids found in soap, except that they are manufactured chemically from materials other than animal fats. Examples include salts called sodium alkylbenzene sulphonates, which have the general structure.

Sodium alkylbenzene sulphonates

Why are detergents preferred over soaps ?

Their advantage over natural soaps is that they work in hard water. The anions of synthetic detergents don’t precipitate in the presence of Ca2+ / Mg2 , so their cleansing action is not affected by hard water.

Types of Detergents :

Detergents are mainly classified into three categories namely anionic, cationic and non-ionic. Long chain alcohols are used in the manufacture of some of the synthetic anionic detergents. The long chain alcohols are treated with concentrated sulphuric acid to form alkyl hydrogen sulfates of high molecular mass and finally the alkyl sulfates are neutralized with alkali to form salts.

CH3-(CH2)16 CH2OH+H2SO4 CH3 - (CH2)16 CH2OSO3H
          (Lauryl alcohol)                                             Na OH (sq)
                                                                CH3 (CH2)16 CH2OS-O3Na+
                                                                        Anionic Detergent
A detergent of the above type is an anionic detergent, named so as a large part of the molecule is an anion. The single anionic detergent in largest use today in household detergents is alkylbenzene sulphonate.

1. The anionic detergents are also effective in slightly acidic solution to form an alkyl hydrogen sulphate which is a soluble material, whereas the soaps react with the acidic solutions to form insoluble fatty acids.

2. A second type of detergents is the cationic detergents. These are mostly acetates or chlorides of quaternary amines. Being more expensive than the anionic detergents they find limited uses. Such detergents however, possess germicidal properties and are used quite extensively as germicides. Cetyltrimethylammonium chloride is an example.

               (Cetyl methyl ammonium bromide)
    (Cationic detergent used in hair conditioner)

3. Some of the detergents are non-ionic, like the esters of high molecular mass formed by reactions between polyethylene glycol and stearic acid.

                  HO (CH2CH2O)n CH2CH2OH
Polyethylene Glycol

CH3 (CH2)16 COOH + HO (CH2 CH2O)n CH2 CH2 OH

                                      - H2O

CH3 (CH2)16 COO (CH2 CH2 O)n CH2 CH2OH

Non-ionic detergent
Some liquid dishwashing detergents are non- ionic type.

Question.7.  Explain the following types of substances with one suitable example, for each case:
(i) Cationic detergents
(ii) Food preservatives
(iii) Analgesics    
Answer: (i) Cationic detergents : They are quaternary
ammonium salts of amines with acetates, chlorides or bromides as anions and the cationic part possess a long hydrocarbon chain, and a positive charge on nitrogen atoms. Therefore they are called cationic detergents.
Example: Cetyltrimethylammonium bromide

(ii)  Food preservatives : They are used to prevent spoilage of food due to microbial growth.
Example: Table salt, vegetable oils, sodium benzoate, etc.

(iii)  Analgesics: Analgesics reduce or abolish pain without causing impairment of consciousness, mental confusion, in coordination or paralysis or some other disturbance of the nervous system. 

They are of two types:
(a) Non-narcotic analgesics
Example: Aspirin
(b) Narcotic analgesics
Example: Morphine

Question.8.  How do antiseptics differ from disinfectants?
Answer:

Question 9.  What are the following substances? Give one example of each type.  
(i) Antacid
(ii) Non-ionic detergents
(iii)  Antiseptics
Answer:   (i) Antacid: Those substances which neutralize the excess acid and raise the pH to an appropriate level in the stomach are called antacids. Example: Sodium bicarbonate, Mg(OH)2.

(ii) Non Ionic detergents : These are esters of high molecular mass alcohols obtained by reaction between polyethylene glycol and stearic acid.
Example:

HO (CH2CH2O)n CH2 CH2 OH  

CH3(CH2)16 COO (CH2CH2O)n CH2 CH2OH

                  Polyethylene glycol stearate

                      (a non-ionic detergent )

(iii) Antiseptics : These are chemical substances which prevent the growth of microorganisms and may even kill them and are safe to be applied on living tissues. Example: Furacin, soframycin, etc.

Question.10. What are the following substances? Give one example of each of them.

(i) Cationic detergents

(ii) Enzymes

(iii) Sweetening agents

Answer: 

(i) Cationic detergent: Cationic detergents are quaternary ammonium salts of amines with anions as acetates, chlorides or bromides. 

(ii) Enzymes : Enzymes are biological catalysts which are chemically globular proteins having high molecular mass and highly specific in their actions due to presence of active sites of definite shape and size on their surfaces so that only specific substrate can fit in them. 

Example: Pepsin, amylase.

(iii) Sweetening agents: Those chemical substances which are sweet in taste but do not add any calories to our body are called artificial sweetening agents. These are excreted as such through urine. 

Example : Saccharin, aspartame, etc.'

Question.11.  What are analgesic medicines? How are they classified and when are they commonly recommended for use?   
Answer:
Analgesic medicine: Drugs which reduce or abolish pain without causing reduction of consciousness, mental confusion, incoordination or paralysis or some other disorder of the nervous system are called analgesic medicines.
They are classified into the following two categories :

1. Non-narcotic (non-addictive) drugs ’    

2. Example: Aspirin, Ibuprofen.

3. Narcotic (addictive) drugs

4. Example: Morphine, Heroin.

They are recommended with-proper prescription because they are habit forming drugs.

Question.12. Explain the following terms with one example in each case:
1. Food preservatives
2. Enzymes
3. Food preservatives    
Answer:

1. Food preservatives: They are used to prevent spoilage of food due to microbial growth. 

Example: Table salt, vegetable oils, sodium benzoate, etc.

2. Enzymes : The enzymes may be defined as bio-catalysts which catalyze the biochemical reactions in the living organisms. 

Example : Pepsin and Amylase.

3. Detergents : They may be defined as ammonium, sulphonate or sulfate salts of long chain hydrocarbons containing 12 - 18 carbon atoms. 

Example : Sodium lauryl sulfate.

Question.13. Why do we need to classify drugs in different ways?

Answer: Drugs are classified in following different ways:

(a) Based on pharmacological effect.

(b) Based on action on a particular biochemical process.

(c) Based on chemical structure.

(d) Based on molecular targets.

Each classification has its own usefulness.

(а) Classification based on pharmacological effect is useful for doctors because it provides them the whole range of drugs available for the treatment of a particular disease.

(b) Classification based on action on a particular biochemical proc*ess is useful for choosing the correct compound for designing the synthesis of a desired drug.

(c) Classification based on chemical structure helps us to design the synthesis of a number of structurally similar compounds having different substituents and then choosing the drug having least toxicity.

(d) Classification on the basis of molecular targets is useful for medical chemists so that they can design a drug which is most effective for a particular receptor site.

Question.14. Answer the following questions:
1. Why do soaps not work in hard water?
2. What are the main constituents of dettol?
3. How do antiseptics differ from disinfectants?
Answer:

1. Hard water contains insoluble calcium and magnesium chlorides which forms insoluble precipitate (scum) with soap and thus cannot be rinsed off easily.

2. Dettol is a mixture of chloroxylenol and a-terpineol in a suitable solvent.

3.  Antiseptics and disinfectants are effective against microorganisms. However, antiseptics are applied to the living tissues such as wounds, cuts, ulcers, and diseased skin surfaces, while disinfectants are applied to inanimate objects such as floors, drainage system, instruments, etc.

Question.15. What are the following substances? Give one example of each.
1. Food preservatives
2. Synthetic detergents
3. Antacids   
Answer:

1. Food preservatives: They are used to prevent spoilage of food due to microbial growth. 

Example: Table salt, vegetable oils, sodium benzoate etc.

2. Synthetic detergents: Synthetic detergents are cleansing agents which have all the properties of soap but which actually do not contain any soap. 

Example: Sodium Lauryl sulfate (or any one other).

3. Antacids: Those substances which neutralize the excess acid and raise the pH to an appropriate level in the stomach are called antacids. Example: Sodium bicarbonate, Mg(OH)2.

Question.16.
(a) Differentiate between a disinfectant and an antiseptic. Give one example of each.
(b) What is tincture of iodine and what is it used for?    
Answer:
(a) Antiseptics and disinfectants are effective against microorganisms. However, antiseptics are applied to the living tissues such as wounds, cuts, ulcers, and diseased skin surfaces, while disinfectants are applied to inanimate objects such as floors, drainage system, instruments, etc.

(b) Tincture of iodine is 2 -3 % solution of iodine in alcohol and water. Use: It is used as a powerful antiseptic and applied on wounds to kill and prevent growth of microorganisms.

Question 17.
What are the following substances? Give one example of each.
1. Antihistamines
2. Tranquillisers
3. Broad spectrum antibiotics   
Answer:

1. Antihistamines: Antihistamines are amines which are used as drugs to control the allergy effects produced by histamine.

Example: Terfenadine.

2. Tranquilizers: Tranquilizers are a class of chemical compounds used for the treatment of stress, and mild or even severe mental disease. 

Example: Equanil.

3. Broad spectrum antibiotics : Antibiotics which kill or inhibit a wide range of Gram-positive and Gram negative bacteria are said to be broad spectrum antibiotics. 

Example: Chloramphenicol.

Question.18.
1. Name the sweetening agent used in the preparation of sweets for a diabetic patient.
2. What are antibiotics? Give an example.
3. Give two examples of macromolecules that are chosen as drug targets.    
Answer:

1. Saccharin is used for a diabetic patient for preparation of sweets.

2. Antibiotics: Antibiotics are chemical substances produced by a living organism that kill or stop the growth of disease-causing microorganisms such as fungi and bacteria.

3. Carbohydrates, proteins, nucleic acid etc.

Question.19. What are biodegradable and non-biodegradable detergents? Give one example of each.
Answer: 
Biodegradable detergents: Detergents, having straight hydrocarbon chains that are easily degraded or decomposed by micro-organism, are known as biodegradable detergents.
Example : Sodium lauryl sulfate.

Non-biodegradable detergents: Detergents containing branched hydrocarbon chains and are not easily decomposed by the microorganisms, are known as non- biodegradable detergents.
Example: Sodium 4-( 1 , 3 , 5 , 7 tetramethylbutyl) benzene sulphonate.

Question.20. Answer the following:
1. Why is the use of aspartame limited to cold foods and drinks?   
2. How do antiseptics differ from disinfectants?
3. Why do soaps not work in hard water?
Answer:

1. Use of aspartame is limited to cold foods and soft drinks because it is unstable at cooking temperature.

2. Antiseptics and disinfectants are both widely used to control infections. They kill microorganisms such as bacteria, viruses, and fungi using chemicals called biocides. Disinfectants are used to kill germs on nonliving surfaces. Antiseptics kill microorganisms on your skin.

3. Hard water contains insoluble calcium and magnesium chlorides which form insoluble ppt (scum) with soap and thus cannot be rinsed off easily.

Question.21. Write the therapeutic action of following on human body and mention the class of drugs to which each of these belong:
1. Ranitidine
2. Morphine
3. Aspirin    
Answer:  

1. Ranitidine belongs to antacids and it neutralizes the excess acid and raises the pH to an appropriate level in the stomach.

2. Morphine belongs to narcotic analgesics and relieves pain and produces sleep even when taken in small doses.

3. Aspirin belongs to a non-narcotic analgesic and it inhibits the synthesis of compounds that stimulate inflammation in the tissues causing pain. Aspirin relieves pain and fever.

Question.22. Label the hydrophilic and hydrophobic parts in the following compounds.

(i) CH3 (CH2)10OSO3-Na+

(ii) CH3(CH2)15-N+(CH3)3Br-

(iii) CH3(CH2)16COO(CH2CH2O)11 CH2CH2OH

Answer:

Question.23. What are biodegradable and non-biodegradable detergents? Give one example of each.

Answer: Detergents having straight chain hydrocarbons are easily degraded (or decomposed) by microorganisms and hence are called biodegradable detergents while detergents containing branched hydrocarbon chains are not easily degraded by the microorganisms find hence are called non-biodegradable detergents. Consequently, non-biodegradable detergents accumulate in rivers and waterways thereby causing severe water pollution. Examples of biodegradable detergents are sodium lauryl sulfate, sodium 4-(1-dodecyl) benzene sulfonate and sodium 4-(2-dodecyl) benzenesulfonate.

Examples of non-biodegradable detergents are sodium 4-(1 , 3 , 5 , 7 -tetramethyloctane) benzene sulphonate.

Question.24. Explain the following terms with suitable examples:

(i) cationic detergents (ii) anionic detergents and (iii) non-ionic detergents

Answer:

(i) Cationic detergents: These are quaternary ammonium salts, chlorides, acetates, bromides etc containing one or more long chain alkyl groups. For example, cetyltrimethylammonium chloride.

(ii) Anionic detergents are called so because a large part of their molecules are anions. ‘These are of two types:

(a) Sodium alkyl sulfates: For example, sodium lauryl sulfate, C11H23CH2OSO3 Na+ .

(b) Sodium alkylbenzene sulphonates.For example, sodium 4-(1-dodecyl) benzene suLphate (SDS).

(iii) Neutral or non-ionic detergents: These are esters of high molecular mass alcohols with fatty acids. These can also be obtained by treatment of long chain alcohols with excess of ethylene oxide in presence of a base. For example, polyethylene glycol stearate, CH3(CH2)!6COO (CH2CH2O)11 CH2CH2OH Polyethylene glycol stearate.

Question.25. What are food preservatives?
Answer:  Preservation has a major role in the food products. Chemically preserved squashes and crushes can be kept for a fairly long time even after opening the seal of the bottle.
A preservative may be defined as the substance which is capable of inhibiting or arresting the process of fermentation, acidification or any other decomposition of food. Salting i.e. addition of table salt is a well known method for food preservation and was applied in ancient times for preserving raw mangoes, tamarind, meat, fish etc. Sugar syrup can also act as a preservative. Vinegar is a useful preservative for pickles. Apart from these, sulphur dioxide and benzoic acid can be employed for the preservation of food. The major source of sulphur dioxide is potassium metabisulphite (K2S2O5). It is fairly stable in neutral and alkaline medium but gets decomposed by weak acids such as carbonic, citric, tartane and malic acids. Benzoic acid is used either as such or in the form of sodium benzoate. However, sulphur dioxide has a better preservative action than sodium benzoate against bacteria and moulds. It also retards the development of yeast in juice but fails to arrest their multiplication once the number has reached a high value. Sorne salts of sorbic acid and propionic acid are also being used these days for the preservation of the food.
The use of preservatives must be properly controlled as their indiscriminate use is likely to be harmful. The preservative should not be injurious to health and should be also non-irritant.