NCERT Solutions For Class 12 Chemistry Chapter 16 Chemistry in Everyday Life

NCERT Exercise Solutions – Chemistry Chapter 16 Chemistry in Everyday Life

16.1 Why do we need to classify drugs in different ways?

Ans – The following are the drug classifications and the justifications for each classification:

(i)According to pharmacological effect:

This classification gives clinicians access to the whole spectrum of medications available for treatment of a specific kind of issue. Therefore, a classification like this is very helpful to doctors.

(ii) In light of how a medicine acts:

This categorization is based on how a medicine affects a specific biological process.

This categorisation is crucial as a result.

(iii) Based on chemical composition:

This classification includes a list of medications with similar structural characteristics and having identical pharmacological effects frequently.

(iv) Using molecular targets as a basis:

Drugs with the same mechanism of action are made available to medicinal chemists by this classification a target action.

16.2 Explain the term, target molecules or drug targets as used in medicinal chemistry.

Ans – Drug targets in medicinal chemistry are the important molecules involved in particular metabolic pathways that lead to particular illnesses. Examples of pharmacological targets include nucleic acids, proteins, lipids, and carbohydrates.

Drugs are chemical agents that bind to the active sites of the important molecules to inhibit these target molecules.

16.3 Name the macromolecules that are chosen as drug targets.

Ans – Drug targets include proteins, carbohydrates, lipids, and nucleic acids.

16.4 Why should not medicines be taken without consulting doctors ?

Ans – A drug may be hazardous for some receptor sites since it can bind to several receptor sites. Furthermore, using medications in higher doses than suggested typically results in negative side effects. Therefore, in such circumstances, medications may be poisonous. So, it is advised to always see a doctor before taking any medications.

16.5 Define the term chemotherapy.

Ans – Chemotherapy is the term for the use of chemicals for therapeutic purposes. As an illustration, consider the use of chemicals in illness prevention, diagnosis, and treatment.

16.6 Which forces are involved in holding the drugs to the active site of enzymes ?

Ans – The following forces are involved in holding the drugs to the active site of enzymes:
(a) Hydrogen bonding
(b) van der Waals interactions
(c) Ionic bonding
(d) Dipole-dipole interactions

16.7 While antacids and antiallergic drugs interfere with the function of histamines, why do these not interfere with the function of each other ?

Ans – They don’t affect each other’s ability to function because they each target a different body receptor. Pepsin and hydrochloric acid are secreted in the stomach as a result of histamine’s stimulation. The purpose of the medication cimetidine (antacid) is to stop histamine from interacting with the receptors found in the stomach wall. Less acid was released as a result of this. Antihistamines and allergy medications target various receptors.

16.8 Low level of noradrenaline is the cause of depression. What type of drugs are needed to cure this problem ? Name two drugs.

Ans – To mitigate the effects of depression, antidepressant medications are required. These medications stop the enzymes from degrading the neurotransmitter noradrenaline. The crucial neurotransmitter is consequently slowly metabolised, allowing it to continue activating its receptor for a longer period of time.

There are two antidepressants:

iproniazid and phenelzine.

16.9 What is meant by the term ‘broad spectrum antibiotics’ ? Explain.

Ans – broad spectrum antibiotics  Antibiotics with a broad spectrum of activity are efficient against a variety of pathogenic microorganisms.

Chloramphenicol It was discovered in 1947 and is a broad-spectrum antibiotic. It can be administered orally because the gastrointestinal tract quickly absorbs it. Typhoid, diarrhoea, acute fever, several types of urinary infections, meningitis, and pneumonia can all be treated successfully with it.

16.10 How do antiseptics differ from disinfectants ? Give one example of each.

Ans – By altering the solution’s concentration, the same chemical can frequently perform both disinfection and antiseptic functions. For instance, phenol’s 0.2% solution functions as an antiseptic and its 1% solution as a disinfectant. In India, chlorine is used to disinfect water at concentrations of 0.2 to 0.4 ppm (parts per million). Squashes are sterilised with a low proportion of sulphur dioxide before being preserved. There are a few ways that antiseptics and disinfectants differ from one another.

1. Can kill or prevent the growth of micro-organisms.1.Can kill micro-organisms.
2. Do not harm the living tissues. Therefore, these can be applied to the skin.2. Toxic to the living tissues. Therefore, these cannot be applied to the skin.
3. These are used for the dressing of wounds, ulcers and in the treatment of diseased skin.3. These are used for disinfecting floors, toilets, drains, instruments etc.

16.11 Why are cimetidine and ranitidine better antacids than sodium hydrogencarbonate or magnesium or aluminium hydroxide ?

Ans – Since they balance the stomach’s acidity, sodium bicarbonate and the hydroxides of magnesium or aluminium are both excellent antacids. However, using them for an extended period of time may result in the stomach producing too much acid. Ulcers may develop as a result, which is highly hazardous. Ranitidine and cimetidine are both superior salts that have no negative side effects.

16.12 Name a substance which can be used as an antiseptic as well as disinfectant.

Ans – Both an antiseptic and a disinfectant can be made from phenol. Phenol is used as an antiseptic in solutions of 0.2% and as a disinfectant in solutions of 1%.

16.13 What are the main constituents of dettol ?

Ans – The main constituents of antiseptic Dettol are chloroxylenol and terpenol.

chloroxylenol and terpenol.

16.14 What is tincture of iodine ? What is its use ?

Ans – Iodine is dissolved in alcohol and water at a concentration of 2% to 3% to create an iodine tincture. It is used as an antibacterial on wounds.

16.15 What are food preservatives ?

Ans – Chemicals called food preservatives guard against food degradation brought on by microbial development. Some common food preservatives include table salt, sugar, vegetable oil, sodium benzoate (C6H3COONa), and salts of propanoic acid.

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.

16.16 Why is use of aspartame limited to cold foods and drinks ?

Ans – This is because it decomposes at baking or cooking temperatures, making it only suitable for use as an artificial sweetener in cold foods and beverages.

16.17 What are artificial sweetening agents ? Give two examples.

Ans – Traditional sweeteners like sugar (sucrose), which are composed of carbohydrates, are vital nutrients in our diet. People today lead sedentary lives with little time for exercise, making it challenging to burn the excess calories that carbs produce. Artificial sweeteners are substances created by chemists that give food the desired sweet flavour while barely affecting the body’s calorie intake. Saccharin, which is roughly 550 times sweeter than cane sugar, is the most widely used artificial sweetener. For diabetic patients who don’t want to consume carbs (sugar), which will likely result in an increase in calories, it is a blessing. These days, there are also a variety of alternative sweeteners accessible.

artificial sweetening agents

16.18 Name the sweetening agent used in the preparation of sweets for a diabetic patient.

Ans – Sweets for diabetes patients can be made using artificial sweeteners such saccharin, alitame, and aspartame.

16.19 What problem arises in using alitame as artificial sweetener ?

Ans – A strong artificial sweetener, aletame. As a result, it is challenging to manage how sweet the dish is that it is added to.

16.20 How are synthetic detergents better than soaps ?

Ans – In soft water, soaps function. They are ineffective in hard water, though. Contrarily, synthetic detergents function in both hard and soft water.

Soaps are inferior to synthetic detergents as a result.

16.21 Explain the following terms with suitable examples
(i) cationic detergents
(ii) anionic detergents and
(iii) non-ionic detergents.

Ans – (i)Cationic detergents: These consist of one or more long chain alkyl groups and are comprised of quaternary ammonium salts, chlorides, acetates, bromides, etc. Take cetyltrimethyl ammonium chloride as an illustration.

(ii) Detergents that contain anionic hydrophilic groups are known as anionic detergents. These are typically created by reacting long-chain alcohols with intense sulfuric acid to create alkyl hydrogen sulphates. These are then neutralised with alkali to produce salts that can dissolve in water.

Below are a few instances:

The sodium salts of sulphonic acid esters of long-chain aliphatic alcohols, which typically have 10 to 15 carbon atoms, are known as sodium alkyl sulphates.

(iii) Neutral or non-ionic detergents: These are esters of fatty acids and high molecular weight alcohols. These can also be produced by treating long chain alcohols with too much ethylene oxide when a base is present. As an illustration, consider polyethylene glycol stearate, or CH3(CH2)16COO (CH2CH2O)11 CH2CH2OH.

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

Ans – The term “biodegradable detergents” refers to detergents that can be broken down by microbes. These detergents have hydrocarbon chains that are straight. One illustration is sodium lauryl sulphate.

Non-biodegradable detergents are those that are resistant to bacterial microbial microbial degradation.

These detergents have hydrocarbon chains with several branches. As an illustration, consider sodium -4-(1, 3, 5, 7-tetramethyloctyl)benzene sulphonate.

16.23 Why do soaps not work in hard water ?

Ans – Higher fatty acids like palmitic acid (C15H31COOH), oleic acid (C17H33COOH), and stearic acid are water-soluble sodium or potassium salts in soaps (C17H35COOH). Certain calcium and magnesium salts found in hard water react with soap to create the equivalent magnesium compounds. Due to their intractable nature, these separate into curdy, white precipitates, wasting soap.

16.24 Can you use soaps and synthetic detergents to check the hardness of water ?

Ans – Since soaps react with hard water to generate insoluble precipitates of calcium and magnesium salts, they can be used to test the hardness of water. Detergents cannot test the water’s hardness because they do not produce any precipitate.

16.25 Explain the cleansing action of soaps.

Ans – The hydrophilic sections of the stearate ions project outside the oil droplet while the hydrophobic parts of the stearate ions connect to the oil droplet as soap molecules form micelles around an oil droplet (dirt). The stearate ions (together with the dirt) are drawn into water by the hydrophilic, polar components, which removes the dirt from the fabric.

16.26 If water contains dissolved calcium hydrogencarbonate, out of soaps and synthetic detergents which one will you use for cleaning clothes ?

Ans – Water becomes hard due to calcium hydrogencarbonate. As a result, soap cannot be used since hard water causes it to precipitate. However, because a synthetic detergent’s calcium salt is similarly soluble in water, it does not precipitate in hard water. Consequently, you can use synthetic detergents to wash your garments in hard water.

16.27 Label the hydrophilic and hydrophobic parts in the following compounds.
(i)cCH3(CH2)10CH2OSO3 –Na+
(ii) CH3(CH2)15 -N+(CH3)3Br–
(iii) CH3(CH2)16C00(CH2CH2O)11CH2CH2OH

Ans –

hydrophilic and hydrophobic

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