Selina Textbook Solutions: Introduction to Chemistry | Chemistry Class 6 ICSE PDF Download

 Page 1


Points To Remember 
1. Science : “Science is the systematic effort by human being to study, understand 
and utilise nature for meaningful purposes. This understanding is slowly 
developed by careful observations and experiments.” 
2. Chemistry: “The branch of science that deals with the study of the composition, 
physical and chemical properties of various forms of matter is called chemistry.” 
3. Fertilisers : “Are the chemicals which provide nutrients to crops and increase 
their yield.” e.g. Urea, calcium nitrate, sodium nitrate, potash, ammonium sulphate 
etc. 
4. Pesticides : “Are the chemicals used to kill pests which affect the production of 
crops and fruits.” e.g. Aldrin, malathion, parathion etc. 
5. Insecticides are the chemical used to kill insects, e.g. D.D.T. and B.H.C. 
6. Fungicides are substances which protect the crops from fungi, e.g. Bordeaux 
mixture and sulphur act as fungicides. 
7. Hormones are group of chemicals secreted in our body to control various 
activities. 
8. Enzymes are the chemicals secreted by our body and react with food water and 
oxygen as raw material in mouth and intestines. 
9. Role of Chemistry : Without chemistry our life would have been dull, it has 
helped us in every field of life. The production of better and faster crops to meet 
the needs of such a huge population is possible only because of chemicals 
produced by chemistry, i.e. Pesticides, fungicides, insecticides preservatives help 
us to preserve food in a better state and of good taste for a long time. 
In Industry : paints, drugs, fibres, soap, toothpaste, dyes plastics even fuels, 
atomic energy, petrol, diesel, kerosene, wax, paraffin rubber, acids, alkalies 
metals alloys are the gift of chemistry. 
Medicines: Penicillin, Tetracycline, pain killers and various other antibiotics are 
used to kill germs and cure diseases. Building and Daily Life: Building materials, 
items of daily use like, ink, pen, glass, sugar, common salt, paper. 
10. Preservatives are the chemicals which maintain the taste for longer time and do 
not let the food degrade to produce obnoxious (unpleasant smell), e.g. sugar, 
common salt, sodium benzoate and sodium meta-bisulphate. 
Exercise 
Question 1. 
Give two examples for each of the following substances : 
(a) food preservatives 
(b) fuel 
(c) fungicides 
(d) medicines 
(e) building materials 
(f) chemical war weapons 
Page 2


Points To Remember 
1. Science : “Science is the systematic effort by human being to study, understand 
and utilise nature for meaningful purposes. This understanding is slowly 
developed by careful observations and experiments.” 
2. Chemistry: “The branch of science that deals with the study of the composition, 
physical and chemical properties of various forms of matter is called chemistry.” 
3. Fertilisers : “Are the chemicals which provide nutrients to crops and increase 
their yield.” e.g. Urea, calcium nitrate, sodium nitrate, potash, ammonium sulphate 
etc. 
4. Pesticides : “Are the chemicals used to kill pests which affect the production of 
crops and fruits.” e.g. Aldrin, malathion, parathion etc. 
5. Insecticides are the chemical used to kill insects, e.g. D.D.T. and B.H.C. 
6. Fungicides are substances which protect the crops from fungi, e.g. Bordeaux 
mixture and sulphur act as fungicides. 
7. Hormones are group of chemicals secreted in our body to control various 
activities. 
8. Enzymes are the chemicals secreted by our body and react with food water and 
oxygen as raw material in mouth and intestines. 
9. Role of Chemistry : Without chemistry our life would have been dull, it has 
helped us in every field of life. The production of better and faster crops to meet 
the needs of such a huge population is possible only because of chemicals 
produced by chemistry, i.e. Pesticides, fungicides, insecticides preservatives help 
us to preserve food in a better state and of good taste for a long time. 
In Industry : paints, drugs, fibres, soap, toothpaste, dyes plastics even fuels, 
atomic energy, petrol, diesel, kerosene, wax, paraffin rubber, acids, alkalies 
metals alloys are the gift of chemistry. 
Medicines: Penicillin, Tetracycline, pain killers and various other antibiotics are 
used to kill germs and cure diseases. Building and Daily Life: Building materials, 
items of daily use like, ink, pen, glass, sugar, common salt, paper. 
10. Preservatives are the chemicals which maintain the taste for longer time and do 
not let the food degrade to produce obnoxious (unpleasant smell), e.g. sugar, 
common salt, sodium benzoate and sodium meta-bisulphate. 
Exercise 
Question 1. 
Give two examples for each of the following substances : 
(a) food preservatives 
(b) fuel 
(c) fungicides 
(d) medicines 
(e) building materials 
(f) chemical war weapons 
Answer: 
Two examples of : 
(a) Food preservatives : 
1. Sodium Benzoate 
2. Sodium metabisulphate 
3. Sugar 
4. Common salt 
(b) Fuel: 
1. L.P.G. 
2. Petrol 
3. Coal 
(c) Fungicides : 
1. Sulphur 
2. Bordeaux mixture 
(d) Medicines : 
1. Penicillin 
2. Painkillers 
3. Antibiotics 
(e) Building materials : 
1. Cement 
2. Steel 
3. Glass 
(f) Chemical war weapons : 
1. TNT 
2. RDX 
Question 2. 
Give short answers : 
(a) What is science ? 
(b) What is chemistry ? 
(c) What is a fuel ?  
(d) How is chemistry helpful in improving the health of human beings ? 
(e) What is alchemy? 
Page 3


Points To Remember 
1. Science : “Science is the systematic effort by human being to study, understand 
and utilise nature for meaningful purposes. This understanding is slowly 
developed by careful observations and experiments.” 
2. Chemistry: “The branch of science that deals with the study of the composition, 
physical and chemical properties of various forms of matter is called chemistry.” 
3. Fertilisers : “Are the chemicals which provide nutrients to crops and increase 
their yield.” e.g. Urea, calcium nitrate, sodium nitrate, potash, ammonium sulphate 
etc. 
4. Pesticides : “Are the chemicals used to kill pests which affect the production of 
crops and fruits.” e.g. Aldrin, malathion, parathion etc. 
5. Insecticides are the chemical used to kill insects, e.g. D.D.T. and B.H.C. 
6. Fungicides are substances which protect the crops from fungi, e.g. Bordeaux 
mixture and sulphur act as fungicides. 
7. Hormones are group of chemicals secreted in our body to control various 
activities. 
8. Enzymes are the chemicals secreted by our body and react with food water and 
oxygen as raw material in mouth and intestines. 
9. Role of Chemistry : Without chemistry our life would have been dull, it has 
helped us in every field of life. The production of better and faster crops to meet 
the needs of such a huge population is possible only because of chemicals 
produced by chemistry, i.e. Pesticides, fungicides, insecticides preservatives help 
us to preserve food in a better state and of good taste for a long time. 
In Industry : paints, drugs, fibres, soap, toothpaste, dyes plastics even fuels, 
atomic energy, petrol, diesel, kerosene, wax, paraffin rubber, acids, alkalies 
metals alloys are the gift of chemistry. 
Medicines: Penicillin, Tetracycline, pain killers and various other antibiotics are 
used to kill germs and cure diseases. Building and Daily Life: Building materials, 
items of daily use like, ink, pen, glass, sugar, common salt, paper. 
10. Preservatives are the chemicals which maintain the taste for longer time and do 
not let the food degrade to produce obnoxious (unpleasant smell), e.g. sugar, 
common salt, sodium benzoate and sodium meta-bisulphate. 
Exercise 
Question 1. 
Give two examples for each of the following substances : 
(a) food preservatives 
(b) fuel 
(c) fungicides 
(d) medicines 
(e) building materials 
(f) chemical war weapons 
Answer: 
Two examples of : 
(a) Food preservatives : 
1. Sodium Benzoate 
2. Sodium metabisulphate 
3. Sugar 
4. Common salt 
(b) Fuel: 
1. L.P.G. 
2. Petrol 
3. Coal 
(c) Fungicides : 
1. Sulphur 
2. Bordeaux mixture 
(d) Medicines : 
1. Penicillin 
2. Painkillers 
3. Antibiotics 
(e) Building materials : 
1. Cement 
2. Steel 
3. Glass 
(f) Chemical war weapons : 
1. TNT 
2. RDX 
Question 2. 
Give short answers : 
(a) What is science ? 
(b) What is chemistry ? 
(c) What is a fuel ?  
(d) How is chemistry helpful in improving the health of human beings ? 
(e) What is alchemy? 
(f) What kind of experiments did Alchemists do? 
(g) What is ‘Philosopher’s stone’ ? 
(h) What is the main difference between alchemy and chemistry? 
(i) Name the chemicals which help in increasing food production. 
(j) Name six such products, which we use daily. 
(k) How is the knowledge of chemistry important to mankind ? 
Answer: 
(a) SCIENCE is the systematic effort by human beings to control nature through 
experiments and observation for their own use. 
OR 
SCIENCE is the systematic ongoing effort by human beings to study understand and 
utilise nature for meaningful purposes. This understanding is slowly developed by 
careful observations and experiment. 
(b) Chemistry : “The branch of science that deals with the study of the composition and 
the physical and chemical properties of various forms of matter is called Chemistry.” 
(c) Fuels : The substances which on burning produce heat energy are called fuels. 
(d) Chemistry is very helpful in improving the health of human beings by providing 
Antibiotics, Pain killers, Pencilin, Tetracycline etc. It has provided us with Vitamins, 
Enzymes, Minerals and Anesthesia (chloroform, formalene etc.) 
(e) The word “Alchemy” has its origin in a Greek word ‘Khemeia’ means “art of 
transmuting metals”. It was partly based on experimentations and partly on spiritual 
discipline. 
(f) ‘Alchemists’ considered to be early chemists. They used all general techniques of 
chemistry in healing humans. Their contribution proved valuable to the society and in 
the advancement of civilization. 
They had contributed to an incredible number of future uses of chemicals, metals, ink, 
paints, cosmetic, medicines, porcelain, etc. 
(g) The goal of alchemy was to find a mythical and magical substance called 
“philosopher’s stone” not a literal stone but wax, liquid or powder with magical power, 
which on heating with a base, iron and copper metals would turn into gold, the purest 
form of matter which would bring wealth, health and immortality. 
(h) Alchemy was both scientific and spiritual. Alchemists never separated them. It also 
lacked a common language for its concepts and processes i.e. there was no 
standardized scientific practice. 
Chemistry was completely separated from ancient traditional alchemy. Still modern 
chemistry in general owes a great deal to alchemy. Alloys are formed by mixing metals 
with other metals and substances. 
(i) Chemicals which help in increasing food production are fertilisers like urea, sodium 
nitrate, potash, ammonium phosphate, calcium nitrate etc. Pesticides like aldrin, 
malathion which are used to kill pests. Insecticides like D.D.T., 
B.H.C. fungicides like sulphur, bordeaux mixture etc. 
(j) Six products of daily use are soap, paints, pen, tooth-paste, cooking oil, potable 
water. 
(k) Importance of chemistry to mankind chemistry plays an important role to provide 
us with things of daily use like toothpaste, soap, detergents, paints, clothes, 
Page 4


Points To Remember 
1. Science : “Science is the systematic effort by human being to study, understand 
and utilise nature for meaningful purposes. This understanding is slowly 
developed by careful observations and experiments.” 
2. Chemistry: “The branch of science that deals with the study of the composition, 
physical and chemical properties of various forms of matter is called chemistry.” 
3. Fertilisers : “Are the chemicals which provide nutrients to crops and increase 
their yield.” e.g. Urea, calcium nitrate, sodium nitrate, potash, ammonium sulphate 
etc. 
4. Pesticides : “Are the chemicals used to kill pests which affect the production of 
crops and fruits.” e.g. Aldrin, malathion, parathion etc. 
5. Insecticides are the chemical used to kill insects, e.g. D.D.T. and B.H.C. 
6. Fungicides are substances which protect the crops from fungi, e.g. Bordeaux 
mixture and sulphur act as fungicides. 
7. Hormones are group of chemicals secreted in our body to control various 
activities. 
8. Enzymes are the chemicals secreted by our body and react with food water and 
oxygen as raw material in mouth and intestines. 
9. Role of Chemistry : Without chemistry our life would have been dull, it has 
helped us in every field of life. The production of better and faster crops to meet 
the needs of such a huge population is possible only because of chemicals 
produced by chemistry, i.e. Pesticides, fungicides, insecticides preservatives help 
us to preserve food in a better state and of good taste for a long time. 
In Industry : paints, drugs, fibres, soap, toothpaste, dyes plastics even fuels, 
atomic energy, petrol, diesel, kerosene, wax, paraffin rubber, acids, alkalies 
metals alloys are the gift of chemistry. 
Medicines: Penicillin, Tetracycline, pain killers and various other antibiotics are 
used to kill germs and cure diseases. Building and Daily Life: Building materials, 
items of daily use like, ink, pen, glass, sugar, common salt, paper. 
10. Preservatives are the chemicals which maintain the taste for longer time and do 
not let the food degrade to produce obnoxious (unpleasant smell), e.g. sugar, 
common salt, sodium benzoate and sodium meta-bisulphate. 
Exercise 
Question 1. 
Give two examples for each of the following substances : 
(a) food preservatives 
(b) fuel 
(c) fungicides 
(d) medicines 
(e) building materials 
(f) chemical war weapons 
Answer: 
Two examples of : 
(a) Food preservatives : 
1. Sodium Benzoate 
2. Sodium metabisulphate 
3. Sugar 
4. Common salt 
(b) Fuel: 
1. L.P.G. 
2. Petrol 
3. Coal 
(c) Fungicides : 
1. Sulphur 
2. Bordeaux mixture 
(d) Medicines : 
1. Penicillin 
2. Painkillers 
3. Antibiotics 
(e) Building materials : 
1. Cement 
2. Steel 
3. Glass 
(f) Chemical war weapons : 
1. TNT 
2. RDX 
Question 2. 
Give short answers : 
(a) What is science ? 
(b) What is chemistry ? 
(c) What is a fuel ?  
(d) How is chemistry helpful in improving the health of human beings ? 
(e) What is alchemy? 
(f) What kind of experiments did Alchemists do? 
(g) What is ‘Philosopher’s stone’ ? 
(h) What is the main difference between alchemy and chemistry? 
(i) Name the chemicals which help in increasing food production. 
(j) Name six such products, which we use daily. 
(k) How is the knowledge of chemistry important to mankind ? 
Answer: 
(a) SCIENCE is the systematic effort by human beings to control nature through 
experiments and observation for their own use. 
OR 
SCIENCE is the systematic ongoing effort by human beings to study understand and 
utilise nature for meaningful purposes. This understanding is slowly developed by 
careful observations and experiment. 
(b) Chemistry : “The branch of science that deals with the study of the composition and 
the physical and chemical properties of various forms of matter is called Chemistry.” 
(c) Fuels : The substances which on burning produce heat energy are called fuels. 
(d) Chemistry is very helpful in improving the health of human beings by providing 
Antibiotics, Pain killers, Pencilin, Tetracycline etc. It has provided us with Vitamins, 
Enzymes, Minerals and Anesthesia (chloroform, formalene etc.) 
(e) The word “Alchemy” has its origin in a Greek word ‘Khemeia’ means “art of 
transmuting metals”. It was partly based on experimentations and partly on spiritual 
discipline. 
(f) ‘Alchemists’ considered to be early chemists. They used all general techniques of 
chemistry in healing humans. Their contribution proved valuable to the society and in 
the advancement of civilization. 
They had contributed to an incredible number of future uses of chemicals, metals, ink, 
paints, cosmetic, medicines, porcelain, etc. 
(g) The goal of alchemy was to find a mythical and magical substance called 
“philosopher’s stone” not a literal stone but wax, liquid or powder with magical power, 
which on heating with a base, iron and copper metals would turn into gold, the purest 
form of matter which would bring wealth, health and immortality. 
(h) Alchemy was both scientific and spiritual. Alchemists never separated them. It also 
lacked a common language for its concepts and processes i.e. there was no 
standardized scientific practice. 
Chemistry was completely separated from ancient traditional alchemy. Still modern 
chemistry in general owes a great deal to alchemy. Alloys are formed by mixing metals 
with other metals and substances. 
(i) Chemicals which help in increasing food production are fertilisers like urea, sodium 
nitrate, potash, ammonium phosphate, calcium nitrate etc. Pesticides like aldrin, 
malathion which are used to kill pests. Insecticides like D.D.T., 
B.H.C. fungicides like sulphur, bordeaux mixture etc. 
(j) Six products of daily use are soap, paints, pen, tooth-paste, cooking oil, potable 
water. 
(k) Importance of chemistry to mankind chemistry plays an important role to provide 
us with things of daily use like toothpaste, soap, detergents, paints, clothes, 
medicines, fertilisers, pesticides, plastics, in preparing fuels, consumer products like 
glass, paper, pencils, pens, in substances used in defence like gunpowder, T.N.T. etc. 
Question 3. 
What is the contribution of chemistry in the following fields ? 
(a) Industry 
(b) Clothings 
(c) Cosmetics 
(d) National Defence 
(e) Medicines 
Answer: 
Contribution of chemistry in the field of : 
(a) Industry : To improve efficiency and production of metals, paints, paper, plastics, 
alloys, textile, pharmaceuticals, electroplating, cosmetics, synthetic fibres etc. 
(b) Clothings: Chemistry is widely used in textile industry which manufactures clothing 
for us. Clothes guard our body from external environment. 
Formation of clothing begins with the knowledge of conversion of fibres into fabrics. 
Fibres can be natural or synthetic. Earlier only natural fibres were known to man such 
as cotton, jute, silk, wool, etc. which were used to produce dress materials, sarees, 
bags, sweaters, shawls, etc. With more development, synthetic fibres were also made 
such as nylon, terylene etc. These fibres are strong, wrinkle resistant and dry quickly. 
They are used to make towels, bed sheets, bags, curtains, carpets, blankets, dress 
materials, etc. 
(c) Cosmetics: The use of talcum powder, skincare creams, lipsticks, eyes and facial 
make up, deodorants, lotions, perfumes, bathing oil, body butter, baby products, etc. It 
is possible to convert various ingredients into usable cosmetics due to knowledge of 
chemistry. 
(d) National Defence : Substances like gunpowder, T.N.T. (trinitrotoluene), phosgene, 
chemical weapons, laughing gas, etc., are all products of chemistry which contribute to 
the national defence. 
(e) Medicines : Extensive researches by chemists have led to the discovery of number 
of medicinal drugs. These drugs help in fighting diseases and have thus increased the 
life span of human beings. 
Examples : Aspirin, paracetamol, antibiotics like penicillin, tetracyline, antiseptics and 
various other medicines used to kill germs and cure diseases and their symptoms. 
Question 4. 
Who is known as Father of chemistry? Why? 
Answer: 
Robert William Boyle is known as ‘Father of Modern Chemistry’. He was an Anglo Irish 
scientist born in Ireland. He was the first to perform experiments under controlled 
conditions and publish his researches with elaborate details of procedure, apparatus 
and observations. Robert Boyle put chemistry on a firm scientific footing transforming it 
Page 5


Points To Remember 
1. Science : “Science is the systematic effort by human being to study, understand 
and utilise nature for meaningful purposes. This understanding is slowly 
developed by careful observations and experiments.” 
2. Chemistry: “The branch of science that deals with the study of the composition, 
physical and chemical properties of various forms of matter is called chemistry.” 
3. Fertilisers : “Are the chemicals which provide nutrients to crops and increase 
their yield.” e.g. Urea, calcium nitrate, sodium nitrate, potash, ammonium sulphate 
etc. 
4. Pesticides : “Are the chemicals used to kill pests which affect the production of 
crops and fruits.” e.g. Aldrin, malathion, parathion etc. 
5. Insecticides are the chemical used to kill insects, e.g. D.D.T. and B.H.C. 
6. Fungicides are substances which protect the crops from fungi, e.g. Bordeaux 
mixture and sulphur act as fungicides. 
7. Hormones are group of chemicals secreted in our body to control various 
activities. 
8. Enzymes are the chemicals secreted by our body and react with food water and 
oxygen as raw material in mouth and intestines. 
9. Role of Chemistry : Without chemistry our life would have been dull, it has 
helped us in every field of life. The production of better and faster crops to meet 
the needs of such a huge population is possible only because of chemicals 
produced by chemistry, i.e. Pesticides, fungicides, insecticides preservatives help 
us to preserve food in a better state and of good taste for a long time. 
In Industry : paints, drugs, fibres, soap, toothpaste, dyes plastics even fuels, 
atomic energy, petrol, diesel, kerosene, wax, paraffin rubber, acids, alkalies 
metals alloys are the gift of chemistry. 
Medicines: Penicillin, Tetracycline, pain killers and various other antibiotics are 
used to kill germs and cure diseases. Building and Daily Life: Building materials, 
items of daily use like, ink, pen, glass, sugar, common salt, paper. 
10. Preservatives are the chemicals which maintain the taste for longer time and do 
not let the food degrade to produce obnoxious (unpleasant smell), e.g. sugar, 
common salt, sodium benzoate and sodium meta-bisulphate. 
Exercise 
Question 1. 
Give two examples for each of the following substances : 
(a) food preservatives 
(b) fuel 
(c) fungicides 
(d) medicines 
(e) building materials 
(f) chemical war weapons 
Answer: 
Two examples of : 
(a) Food preservatives : 
1. Sodium Benzoate 
2. Sodium metabisulphate 
3. Sugar 
4. Common salt 
(b) Fuel: 
1. L.P.G. 
2. Petrol 
3. Coal 
(c) Fungicides : 
1. Sulphur 
2. Bordeaux mixture 
(d) Medicines : 
1. Penicillin 
2. Painkillers 
3. Antibiotics 
(e) Building materials : 
1. Cement 
2. Steel 
3. Glass 
(f) Chemical war weapons : 
1. TNT 
2. RDX 
Question 2. 
Give short answers : 
(a) What is science ? 
(b) What is chemistry ? 
(c) What is a fuel ?  
(d) How is chemistry helpful in improving the health of human beings ? 
(e) What is alchemy? 
(f) What kind of experiments did Alchemists do? 
(g) What is ‘Philosopher’s stone’ ? 
(h) What is the main difference between alchemy and chemistry? 
(i) Name the chemicals which help in increasing food production. 
(j) Name six such products, which we use daily. 
(k) How is the knowledge of chemistry important to mankind ? 
Answer: 
(a) SCIENCE is the systematic effort by human beings to control nature through 
experiments and observation for their own use. 
OR 
SCIENCE is the systematic ongoing effort by human beings to study understand and 
utilise nature for meaningful purposes. This understanding is slowly developed by 
careful observations and experiment. 
(b) Chemistry : “The branch of science that deals with the study of the composition and 
the physical and chemical properties of various forms of matter is called Chemistry.” 
(c) Fuels : The substances which on burning produce heat energy are called fuels. 
(d) Chemistry is very helpful in improving the health of human beings by providing 
Antibiotics, Pain killers, Pencilin, Tetracycline etc. It has provided us with Vitamins, 
Enzymes, Minerals and Anesthesia (chloroform, formalene etc.) 
(e) The word “Alchemy” has its origin in a Greek word ‘Khemeia’ means “art of 
transmuting metals”. It was partly based on experimentations and partly on spiritual 
discipline. 
(f) ‘Alchemists’ considered to be early chemists. They used all general techniques of 
chemistry in healing humans. Their contribution proved valuable to the society and in 
the advancement of civilization. 
They had contributed to an incredible number of future uses of chemicals, metals, ink, 
paints, cosmetic, medicines, porcelain, etc. 
(g) The goal of alchemy was to find a mythical and magical substance called 
“philosopher’s stone” not a literal stone but wax, liquid or powder with magical power, 
which on heating with a base, iron and copper metals would turn into gold, the purest 
form of matter which would bring wealth, health and immortality. 
(h) Alchemy was both scientific and spiritual. Alchemists never separated them. It also 
lacked a common language for its concepts and processes i.e. there was no 
standardized scientific practice. 
Chemistry was completely separated from ancient traditional alchemy. Still modern 
chemistry in general owes a great deal to alchemy. Alloys are formed by mixing metals 
with other metals and substances. 
(i) Chemicals which help in increasing food production are fertilisers like urea, sodium 
nitrate, potash, ammonium phosphate, calcium nitrate etc. Pesticides like aldrin, 
malathion which are used to kill pests. Insecticides like D.D.T., 
B.H.C. fungicides like sulphur, bordeaux mixture etc. 
(j) Six products of daily use are soap, paints, pen, tooth-paste, cooking oil, potable 
water. 
(k) Importance of chemistry to mankind chemistry plays an important role to provide 
us with things of daily use like toothpaste, soap, detergents, paints, clothes, 
medicines, fertilisers, pesticides, plastics, in preparing fuels, consumer products like 
glass, paper, pencils, pens, in substances used in defence like gunpowder, T.N.T. etc. 
Question 3. 
What is the contribution of chemistry in the following fields ? 
(a) Industry 
(b) Clothings 
(c) Cosmetics 
(d) National Defence 
(e) Medicines 
Answer: 
Contribution of chemistry in the field of : 
(a) Industry : To improve efficiency and production of metals, paints, paper, plastics, 
alloys, textile, pharmaceuticals, electroplating, cosmetics, synthetic fibres etc. 
(b) Clothings: Chemistry is widely used in textile industry which manufactures clothing 
for us. Clothes guard our body from external environment. 
Formation of clothing begins with the knowledge of conversion of fibres into fabrics. 
Fibres can be natural or synthetic. Earlier only natural fibres were known to man such 
as cotton, jute, silk, wool, etc. which were used to produce dress materials, sarees, 
bags, sweaters, shawls, etc. With more development, synthetic fibres were also made 
such as nylon, terylene etc. These fibres are strong, wrinkle resistant and dry quickly. 
They are used to make towels, bed sheets, bags, curtains, carpets, blankets, dress 
materials, etc. 
(c) Cosmetics: The use of talcum powder, skincare creams, lipsticks, eyes and facial 
make up, deodorants, lotions, perfumes, bathing oil, body butter, baby products, etc. It 
is possible to convert various ingredients into usable cosmetics due to knowledge of 
chemistry. 
(d) National Defence : Substances like gunpowder, T.N.T. (trinitrotoluene), phosgene, 
chemical weapons, laughing gas, etc., are all products of chemistry which contribute to 
the national defence. 
(e) Medicines : Extensive researches by chemists have led to the discovery of number 
of medicinal drugs. These drugs help in fighting diseases and have thus increased the 
life span of human beings. 
Examples : Aspirin, paracetamol, antibiotics like penicillin, tetracyline, antiseptics and 
various other medicines used to kill germs and cure diseases and their symptoms. 
Question 4. 
Who is known as Father of chemistry? Why? 
Answer: 
Robert William Boyle is known as ‘Father of Modern Chemistry’. He was an Anglo Irish 
scientist born in Ireland. He was the first to perform experiments under controlled 
conditions and publish his researches with elaborate details of procedure, apparatus 
and observations. Robert Boyle put chemistry on a firm scientific footing transforming it 
from alchemy into one based on measurements. He defined elements, compounds and 
mixtures. 
Question 5. 
Name the scientists who discovered the following. 
(a) Atoms 
(b) Oxygen 
(c) Safety lamp 
(d) Elements 
Answer: 
The scientists who discovered 
(a) Atoms : John Dalton was a British chemist and physicist. He proved that matter 
consists of small indivisble called ‘atoms’. For this he proposed the atomic theory which 
was later on called “Dalton’s atomic theory”. 
(b) Oxygen : Joseph Priestly. 
(c) Safety lamp : Sir Humphry Davy. 
(d) Elements : Antoiene Lavoisier was a French nobleman. He revolutionized 
chemistry. Lavoisier named the elements carbon, hydrogen and oxygen and discovered 
the role of oxygen in combustion and respiration for which he is most noted. He 
established that water is a compound and helped to continue the transformation of 
chemistry from a qualitative science to a quantitative one. 
Objective Type Questions 
Question 1. 
Fill in the blanks : 
(a) Chemistry deals with the study of matter and the changes it undergoes. 
(b) Fertilizers help to increase the production of food. 
(c) Food items like jams and pickles are protected by using preservatives (salt and 
sugar). 
(d) L.P.G. is used for fuel. 
(e) Inert gases were discovered by William Ramsay.