Coal and Petroleum - Exemplar Solutions 3
CBSE Class 8 Science
NCERT Exemplar Solutions
CHAPTER 5
Coal and Petroleum
NCERT Exemplar Solutions
CHAPTER 5
Coal and Petroleum
SHORT ANSWER QUESTIONS
20. Sunlight and air are inexhaustible natural resources. Comment.
Ans. Sunlight and air inexhaustible natural resources because they will not get exhausted by human activities as they get renewed naturally in a very span of time. These resources are always available in a limitless quantity in nature.
21. Some natural resources are given in a box. Classify them into the exhaustible and inexhaustible natural resources.
air, coal, natural gas, sunlight, petroleum, minerals, forests, oxygen.
Ans. Exhaustible natural resources are coal, natural gas, petroleum, minerals, forests. Inexhaustible natural resources are air, sunlight, oxygen.
22. Write two important uses of coke.
Ans. It is used for the manufacture of steel and also in extraction of many metals.
23. Write the characteristics and some important uses of coal.
Ans. Coal is black in colour and hard as stone. It is one of the fuels used to cook food. Earlier it was used in railway engines to produce steam to run the engine. It is used as fuel in thermal power plants to produce electricity and in various other industries.
24. Look at Fig. 5.1 where petroleum and natural gas deposits are shown. Why do we find oil layer above water layer?
Ans. Petroleum possess a lesser density than water and hence floats on water. Due to this reasons we find oil layer above water layer.
25. Fill in the blanks and complete the story.
About 300 million years ago the earth had dense ________ in low lying wetland areas. Due to natural processes, like ______, these forests got burried under the ________. As more ________ deposited over them, they were compressed. The ________ also rose as they sank deeper and deeper. Under high ________ and high ________, dead plants got slowly converted into coal.
Ans. forests, floods, soil, soil, temperature, pressure, temperature.
26. Match the items given in Column I with the items of Column II.
Ans. (a)–(iii), (b)–(iv), (c)–(i), (d)–(ii)
