Coal and Petroleum - Exemplar Solutions 2

CBSE Class 8 Science
NCERT Exemplar Solutions
CHAPTER 5
Coal and Petroleum

VERY SHORT ANSWER QUESTIONS
13. You are provided with a mixture of petroleum and water. Can you suggest a method to separate the two?
Ans. Petroleum and water are two immiscible liquids. As hence they can be easily separated by using a separating funnel. Oil due to its lower density than water floats over water.
So, pour the mixture of water and petroleum into a separating funnel and leave it untouched for a while. Soon both the layers will get distinguished. Open the tap of funnel and allow the water a get out of the funnel. The two liquids are now separate.

14. What does CNG stand for and why is it considered to be a better fuel than petrol?
Ans. CNG stands for Compressed Natural Gas. It is considered to be a better fuel because it creates less pollution on heating or burning..

15. Name the petroleum product used as fuel for stoves, lamps and jet aircrafts.
Ans. Kerosene is used as fuel for stoves, lamps and jet aircrafts.

16. Fill in the blanks in the following sentences.
(a) Coal is one of the ________ used to cook food.
(b) When heated in air, coal burns and produces mainly ________ gas.
(c) Coal tar is a black, thick ________ with an ________ smell.
(d) Petroleum, ________ and ________ are fossil fuels.
(e) Forests and coal are ________ natural resources.
Ans. (a) fuels
(b) carbon dioxide
(c) liquid, unpleasant
(d) coal, natural gas
(e) exhaustible

17. The underlined words in the following sentences have been jumbled up. Write them in their correct form.
(a) Loca is obtained from mines.
(b) Umpetlore is a fossil fuel.
(c) Rineryfe is a place where various fractions of peroleum are separated.
(d) Keenrose is a fuel used in jet crafts.
(e) Nutsgilh is an example of inexhaustible natural resources.
Ans. (a) coal (b) petroleum (c) refinery (d) kerosene (e) sunlight

18. Fill in the blanks.
(a) The slow process of conversion of dead vegetation into coal is called__________.
(b) Coal and petroleum are formed from the dead remains of organisms and are known as __________.
(c) The black thick liquid with __________ smell is known as coal tar.
(d) During the processing of coal to get coke, coal tar and __________ are also obtained.
(e) The process of separating the various constituents of petroleum is known as ____.
(f) Excessive burning of fossil fuels is a major cause of __________.
Ans. (a) carbonisation, (b) fossil fuels, (c) unpleasant, (d) coal gas, (e) refining, (f) air pollution.

19. Write True/False against the following statements.
(a) Oxygen in air is an exhaustible natural resource.
(b) Resources which are present in unlimited quantity in nature are called exhaustible natural resources.
(c) Wildlife is an exhaustible natural resource.
(d) Under high temperature and pressure, dead plants get slowly converted to coal.
(e) CNG is less polluting fuel than petrol and diesel.
Ans. (a) False, (b) False, (c) True, (d) True, (e) True.