NCERT solutions for Class 12 Chemistry Chapter 16 Chemistry in Everyday life

Solutions to In-Text Questions Ex 16.1 to 16.5

Question 16.1 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 contain drugs and when drugs are taken in doses higher than recommended may cause harmful effects on our body, it may affect the nervous system; also it may lead to person death. Hence, a doctor should always be consulted before taking any medicins.

Question 16.2 With reference to which classification has the statement, “ranitidine is an antacid” been given?

Answer :

The given statement refers to the classification of the pharmacological effects of the drug. This is because drugs which are used to counteract(decrease the level of HCl) the effect of excess acid secretion in the stomach is known as an antacid. Ranitidine belongs to the class of histamine receptors blockers, where they block the activity of receptors present in the stomach(cause of secretion of gastric acid).

Question 16.3 Why do we require artificial sweetening agents ?

Answer :

Natural sweeteners like sucrose provide calories to the body. For a diabetic patient, we need artificial sweetener because it does not add any type of calories which affect the diabetic patient But in natural sweetener the amount of fat, carbohydrate, protein is high. Examples of artificial sweeteners are- Saccharin, aspartame etc.

Question 16.4 Write the chemical equation for preparing sodium soap from glyceryl oleate and glyceryl palmitate. Structural formulae of these compounds are given below.

(i) – Glyceryl palmitate

(ii) – Glyceryl oleate

Answer :

Soaps used for cleaning purpose are sodium or potassium salts of long chain fatty acids, e.g., stearic, oleic and palmitic acids.
when glyceryl palmitate reacts with sodium hydroxide it gives glycerol and soap molecules.

(i)

(ii)

Question 16.5 Following type of non-ionic detergents are 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.

( x = 5 to 10 )

Answer :

The functional group present in the structure is ether and alcohol group.

NCERT Solutions for Class 12 Chemistry Chapter 16 Chemistry in Everyday Life- Exercise Questions

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

Answer :

We need to classify the drugs in different ways because of-

• Pharmacological effect

This classification provides doctors with the whole range of drugs available for the treatment of a certain type of problem

• Drug action

The action of drugs on a particular biochemical process

• Chemical structure

This classification provides a range of drugs sharing common structural features

• molecular targets

Drugs have some common structural features may have the same mechanism of action on the targets. Hence it is the most useful classification for medicinal chemists

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

Answer :

In medicinal chemistry, drug targets are the key molecules, which involved in certain metabolic pathways that result in specific diseases. Drugs mainly interact with biomolecules such as carbohydrates, lipids, proteins and nucleic acids. Drugs are the chemical agents, and they are designed to inhibit these target molecules by binding with the active sites of the key molecules.

Question 16.3 Name the macromolecules that are chosen as drug targets.

Answer :

The macromolecules that are chosen as drug targets are carbohydrate, lipids, proteins, enzymes and nucleic acid.

Question 16.4 Why should not medicines be taken without consulting doctors ?

Answer :

Medicines should not be taken without consulting doctors because medicins can bind more than one receptor sites. So, it may be toxic for some receptors site. Also if we take medicine dose higher than recommended then it causes a harmful effect on our body and also leads to person death.

Question 16.5 Define the term chemotherapy.

Answer :

chemotherapy
The use of chemicals for therapeutic effect is called chemotherapy. In other words, it means treatment of disease with the help of chemicals For example the use of chemicals in the diagnosis, prevention, and treatment of diseases

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

Answer :

Forces that are involving in holding the drugs to the active sites of enzymes-

• Ionic bonding
• Hydrogen bonding
• Dipole-dipole interaction
• Van der Waals force

Question 16.7 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 the particular receptor site. Both antacids and anti-allergic drugs work on different receptors. So, that's why they do not interfere with each other's functions, but interfere with the function of histamine.

Question 16.8 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 used to minimise the effect of depression. These drugs inhibit enzymes catalysing the degradation of the neurotransmitter, noradrenaline. Thus, this neurotransmitter is slowly metabolised and can activate its receptor for longer periods of time. Two antidepressant drugs are Iproniazid and Phenelzine.

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

Answer :

Broad-spectrum antibiotics-

The range of bacteria that are affected by certain antibiotics has expressed a spectrum of its action.
Antibiotics which kill/inhibit a wide range of Gram-positive and Gram-negative bacteria are said to be broad-spectrum antibiotics. Chloramphenicol is a broad-spectrum antibiotic.

It can be used for the treatment of typhoid, dysentery, acute fever, pneumonia, and certain types of urinary infection.

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

Answer :

Antiseptic and disinfectants are effective against micro-organism. Antiseptics are applied on living tissues such as wound, cuts and diseased skin surfaces. But disinfectants are applied to inanimate objects such as floors, drainage system, instruments etc. Disinfectants are harmful to living tissues.
Examples-, 0.2 per cent solution of phenol is an antiseptic while it is one per cent solution is disinfectant. Iodoform is another antiseptic

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

Answer :

Sodium bicarbonate or magnesium or aluminium hydroxide, these antacids work on by neutralising the excess hydrochloric acid present in the stomach. However, the main cause for the release of excess acid remains untreated. cimetidine and ranitidine better antacids as they treat the root cause of acidity. These drugs prevent the interaction of histamine with the receptor present in the stomach walls. This is why cimetidine and ranitidine are better antacids than sodium hydrogen carbonate, magnesium hydroxide, and aluminium hydroxide.

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

Answer :

Phenol can be used as antiseptic as well as disinfectants. 1 per cent of phenol solution is used as disinfectant while 0.2% of it is used as antiseptic.

Question 16.13 What are the main constituents of dettol ?

Answer :

The main constituent of dettol is chloroxylenol and terpineol.

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

Answer :

Iodine is a powerful antiseptic. Its 2-3 per cent solution in alcohol-water mixture is known as tincture of iodine.

USES-

• It is applied to wounds

Question 16.15 What are food preservatives ?

Answer :

FOOD PRESERVATIVES-
Chemicals that prevent food against bacteria, moulds, yeasts etc., are known as food preservatives. For examples- table salt, sugar, vegetable oil, sodium benzoate, and salt os propanoic acid etc.

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

Answer :

Aspartame becomes unstable at cooking temperature, because of that, its use is limited to cold foods and drinks.

Question 16.17 What are artificial sweetening agents ? Give two examples.

Answer :

Artificial sweetening agents are those chemicals, which are used to sweeten the food. However, unlike natural sweeteners, they don't add calories to our body. They don't harm our body.

Examples- aspartame, saccharin, sucralose, and alitame.

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

Answer :

For a diabetic patient, we use an artificial sweetening agent like saccharine, alitame and aspartame.

Question 16.19 What problem arises in using alitame as artificial sweetener ?

Answer :

Aspartame is a high potency sweetener. It is difficult to control the sweetness of food while using it as a sweetener.

Question 16.20 How are synthetic detergents better than soaps ?

Answer :

Soaps are only work in soft water, and we do not use them effectively in hard water. But synthetic detergents are used effectively in both hard and soft water. That's why these are better than soaps.

Question 16.21(i) Explain the following terms with suitable examples

(i) cationic detergents

Answer :

Cationic detergents -
These are quarternary ammonium salts of acetates, chlorides or bromides. The long hydrocarbon chain part has a cationic charge, a positive charge on the Nitrogen atom. Hence these are called cationic detergents. Example- Cetyltrimethylammonium bromide

Question 16.21 Explain the following terms with suitable examples

(ii) anionic detergents and

Answer :

Anionic detergents-

Anionic detergents are sodium salts of sulfonated long chain alcohols or hydrocarbons. In these detergents, the anionic part of the detergent is involved in cleansing action. They are mostly used for household work. Anionic detergents are also used in toothpaste.

Example- sodium lauryl sulphate and sodium dodecylbenzenesulphonate

Question 16.21 Explain the following terms with suitable examples

(iii) non-ionic detergents

Answer :

Non-ionic detergents-
These types of detergents do not have any charges in their constituent. Such detergent is formed when stearic acid reacts with polyethylene glycol.
example- Liquid dishwashing detergents are non-ionic

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

Answer :

Detergents that are degraded by bacteria are called bio-degradable detergents. These type of detergents has a long straight hydrocarbon chain. Ex- sodium lauryl sulphate.

And detergent that cannot be degraded by bacteria or microbes is called non-biodegradable detergent. Such detergent has highly branched hydrocarbon chains. Ex.- Most of the synthetic detergents.

Question 16.23 Why do soaps not work in hard water ?

Answer :

Hard water contains ions of magnesium and calcium. When we add sodium and potassium soaps in hard water these ions form magnesium and calcium insoluble soaps.

These insoluble salts separate as scum. And this is the reason why soap doesn't work in hard water.

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

Answer :

Soaps can be used to check wheater water is hard or soft. In hard water soaps get precipitated but not in soft water. However, synthetic detergent can work efficiently in both hard and soft water. Thus synthetic detergent cannot be used to check the hardness of the water.

Question 16.25 Explain the cleansing action of soaps.

Answer :

When we add soap in water, it forms micelle around the dirt particle(oil) in such a way that hydrophobic part of the stearate ion is attached with the dirt and the hydrophilic parts pointing towards away from the dirt. Due to polar in nature, the hydrophilic part of the stearate ion is pulled into the water, thereby removing the dirt from the cloth.

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

Answer :

Synthetic detergents are preferred for cleaning cloths. This is because water contains calcium ions, these ions form insoluble salts when we add soap and get precipitated. However, synthetic detergents are working efficiently in both hard and soft water. When we add these detergents in water, these ions form soluble salts that act as cleansing agents.

Question 16.27(i) Label the hydrophilic and hydrophobic parts in the following compounds.

(i)

Answer :

|__________________| |__________|
hydrophobic part hydrophilic part

Question 16.27(ii) Label the hydrophilic and hydrophobic parts in the following compounds.

(ii)

Answer :

|_____________| |_______________|
hydrophobic part hydrophilic part

Question 16.27(iii) Label the hydrophilic and hydrophobic parts in the following compounds.

(iii)

Answer :

|_____________| |_________________________________|
hydrophobic hydrophilic part
part