Class-8 Science Chapter-5 Coal and Petroleum

     EVENTS CONVENT HIGH SCHOOL

18/01/2021                       CLASS-8                                  SLOT-2

 SCIENCE

CHAPTER -5 COAL AND PETROLEUM

_________________________________________________________________

  

Question 1.What are the advantages of using CNG and LPG as fuels?
Answer: The advantages of using CNG and LPG as fuels are:

They burn with a smokeless flame and so does not cause any pollution.

They leave no ash on burning.

They are easy to handle and convenient to store.

Question 2.Name the petroleum product used for surfacing of roads.
Answer:Bitumen

Question 3.Describe how coal is formed from dead vegetation. What is this process called?
Answer:Millions of years ago, trees, plants, ferns and forests got buried below the rocks, soil and sand due to natural processes like flooding, earthquake, etc. Slowly, as more soil deposited over them, they were compressed. This led to the conditions of high pressure and heat. These conditions along with the anaerobic conditions turned the carbon-enriched organic matter of wood into coal.
This slow process of conversion of wood into coal is called carbonisation.

Question 4.Fill in the blanks.
(a) Fossils fuels are coal, petroleum, and natural gas
(b) Process of separation of different constituents from petroleum is called refining
(c) Least polluting fuel for vehicle is CNG

Question 5. Tick True/False against the following statements.
(a) Fossil fuels can be made in the laboratory.                           [False]
(b) CNG is more polluting fuel than petrol.                             [False]
(c) Coke is an almost pure form of carbon.                             [True]
(d) Coal tar is a mixture of various substances.                          [True]
(e) Kerosene is not a fossil Fuel.                                        [False]

Question 6.Explain why fossil fuels are exhaustible natural resources.
Answer:Fossil fuels take millions of years to be formed. They are limited in nature and cannot be replenished easily, once consumed. Hence, they are considered as exhaustible natural resources.

Question 7.Describe the characteristics and uses of coke.
Answer:Characteristics of coke: Coke is 98% pure carbon. It is a tough, porous and black substance. It pro-duces a very little smoke.
Uses of coke: Coke is very useful as fuel. It is a good reducing agent. It is widely used in metallurgical processes to reduce metals from their oxides. It is used for producing water gas.

Question 8.Explain the process of the formation of petroleum.
Answer:Petroleum is formed by the burial of aquatic plants and animals below the sea bed. The marine animals and plants died thousands of years ago and settled down in the bottom of sea. In anaerobic conditions, microorganisms decompose this organic matter. Due to high pressure and heat, the dead remains of tiny plants and animals were slowly converted into petroleum

Question- 9 Extra Questions in Very short:-
Question 1.Write down any four amorphous forms of carbon.
Answer:Amorphous forms of carbon – coal, charcoal, coke and lamp black.

Question 2.Explain the process of formation of petroleum ? Name two places in India where it is found.
Answer:Petroleum is formed by the decomposition of aquatic plants and animal remains. In India, petroleum is obtained from oil wells in Assam and Bombay High.

Question 3.Distinguish between inexhaustible and exhaustible natural resources.
Answer:Exhaustible resources – forests, wildlife, coal
Inexhaustible resources – air, sunlight, water.

Question 4.Why are coal and petroleum known as fossil fuels ?
Answer:Coal and petroleum are formed from the dead remains of living organisms that is why they are called fossils fuels.

Question 5.Give two characteristics of coal.
Answer:Coal is hard and is of black in colour.

Question 6.Define destructive distillation. Name the residue formed by destructive distillation of coal.
Answer:Destructive distillation is the process of heating a substance in absence of air. Coke is formed by destructive distillation of coal.

Question 7.What is meant by refining of petroleum and where is it done ?
Answer:The process of separating the different fractions of petroleum is known as refining and it is carried out in a refinery.

Question 8.Give two uses of diesel.
Answer:Diesel is used as fuel for heavy motor vehicles and in electric generators.

 

Question-10 Extra Questions in Short:-

Question 1.Define the term fossil fuel. Name two fossil fuels. [KVS 2008, 2005]
Answer:Fossil fuels are formed from dead remains of living matter over millions of years when they remained buried under the earth. Coal and petroleum are two fossil fuels.

Question 2.State one use of each of the following : [KVS 2007]

1.Charcoal, 2.Bone Charcoal 3.Coke.

Answer:Use:

Charcoal : Fuel.

Bone Charcoal : Purification of brown coloured sugarcane juice in the manufacture of sugar.

Coke : Used as a reducing agent in the extraction of metals.

Question 3.Name the products obtained when coal is heated in the absence of air.

 Answer:Coke is formed when coal is heated in absence of air.

Coke is used :

As a fuel.

As a reducing agent in the extraction of metals.

Question 4.(a) Give the full form of
(i) LPG(ii) CNG.
(b) How is petroleum gas obtained ?

Answer:(a) (i) LPG — Liquefied Petroleum Gas.
(ii) CNG — Compressed Natural Gas.
(b) Petroleum gas is obtained during fractional distillation of petroleum.

Question 5.Draw diagram to show petroleum and natural gas deposit.
Answer: