NCERT Class 8 Science Chapter 6 Combustion and Flame Extra Questions and Answers
Class 8 Science Chapter 6 Extra Questions and Answers – Combustion and Flame. Here in this Page Class VIII Students can Learn Extra Questions & Answer 6th Chapter Science fully Inside.
We Provided Here Combustion and Flame Science Chapter 6 Long Answer Type Question, Very Short Type Questions (VSA) / MCQ Type Questions, Short Type Questions (SA).
1) Fill in the blanks:
a) ____ is an inflammable substance. (Petrol)
b) ____ is a fire extinguisher. (CO2)
c) ____ is a solid fuel. (Coal)
d) Calorific value of LPG = _____ kJ/kg. (55000)
e) The lowest temperature at which a substance catches fire is called its _____. (Ignition temperature)
2) Multiple choice questions:
a) Calorific value of hydrogen = _____ kJ/kg?
a) 45000 b) 55000 c) 150000
Ans. c) 150000
b) Natural gases are ____ fuel?
a) Solid b) Gaseous c) Liquid
Ans. b) Gaseous
c) ____ is a domestic fuel?
a) LPG b) Petrol c) Diesel
Ans. a) LPG
d) Fire produced by oil can be controlled by ____?
a) H2O b) CO2
Ans. b) CO2
3) Answer the following questions:
a) What is combustible? Give an example.
Ans. The substances which burn in air are called combustible.
Example –cooking gas.
b) Define rapid combustion and spontaneous combustion.
Ans. The type of combustion in which a gas burns rapidly and produce heat and light is known as rapid combustion.
The type of combustion in which a material suddenly bursts into flames, without the application of any apparent cause is called spontaneous combustion.
c) Define inflammable with two examples.
Ans. The substances which have very low ignition temperature and can easily catch fire with a flame are called inflammable.
Examples – Petrol and alcohol.
d) Why the use of diesel and petrol as fuels in automobiles being replaced by CNG?
Ans. The use of diesel and petrol as fuels in automobiles being replaced by CNG because CNG produces the harmful products in very small amounts and it is a cleaner fuel.
e) What are the effects of global warming?
Ans. Global warming means the rise in temperature of the atmosphere of the earth. This results, among other things, in melting of polar glaciers, which leads to a rise in the sea level, causing floods in the coastal areas. Low lying coastal areas may even be permanently submerged under water.
f) ‘For fires involving electrical equipment CO2 is the best extinguisher.’ – explain.
Ans. For fires involving electrical equipment CO2 is the best extinguisher because CO2, being heavier than oxygen, covers the fire like a blanket. Since the contact between the fuel and oxygen is cut off, the fire is controlled. The added advantage of CO2 is that in most cases it does not harm the electrical equipment.
4) Match the items of column I with the information of column II:
Column I Column II
a) PhosphorusI) Incomplete combustion of a fuel gives poisonous gas
b) NitrogenII) caused by increased concentration of CO2 in the air
c) Carbon monoxideIII) Vaporized during burning and form flames
d) Global warming IV) Burns in air at room temperature
e) KeroseneV) Petrol engines give off gaseous oxides of
Ans. a) – IV), b) – V), c) – I), d) – II), e) – III).
5) Mark your answer as per the codes provide below:
a) A: Acid rain is not harmful for crops, buildings and soil.
R: Oxides of sulfur and nitrogen dissolve in rain water and form acids which causes acid rain.
I.) Both A and R are true and R is the correct explanation of A.
II.) Both A and R are true but R is not the correct explanation of A.
III.) A is true but R is false.
IV.) A is false but R is true.
V.) Both A and R are false.
Ans. IV) A is false but R is true.
b) A: It is dangerous to burn coal in a closed room.
R: The incomplete combustion of coal gives carbon monoxide gas which can kill persons sleeping in that room.
I.) Both A and R are true and R is the correct explanation of A.
II.) Both A and R are true but R is not the correct explanation of A.
III.) A is true but R is false.
IV.) A is false but R is true.
V.) Both A and R are false.
Ans. I. Both A and R are true and R is the correct explanation of A.
6) For centuries, wood was used as domestic and industrial fuel. But now it has been replaced by coal and other fuels like LPG. In many rural parts of our country, people still use wood as a fuel because of its easy availability and low cost. However, burning of wood gives a lot of smoke which very harmful for human beings. It causes respiratory problem. Also, trees provide us with useful substances which are lost when wood is used as fuel. Moreover cutting of trees leads to deforestation which is quite harmful to the environment.
a) Cutting of trees leads to ____. (Deforestation)
b) Use of wood as a fuel has been replaced by ____ and ____. (Coal and LPG)
c) What happens when we use wood as a fuel?
Ans. When we use wood as a fuel, the burning of wood gives a lot of smoke which very harmful for human beings. It causes respiratory problem. Also trees provide us with useful substances which are lost when wood is used as fuel.
More Extra Questions and Answers
Q.1) Fill in the blanks
1) A chemical process in which a substance reacts with oxygen to give off heat is called COMBUSTION.
2) LPG is an INFLAMMABLE substance.
3) Increased concentration of carbon dioxide in air is believed to cause GLOBAL WARMING.
4) The calorific value of fuel is expressed in unit KILOJOULE PER KG (Kj/KG).
5) OXYGEN in air essential for combustion.
In case you are missed :- NCERT Extra Questions for Coal And Petroleum
Q.2) Say whether the given statements are true or false
1) Water is commonly used to control fire.
Ans. True
2) Increased percentage of nitrogen in air causes Global warming.
Ans .False
3) Coal is a natural gas.
Ans .True
4) Wood , charcoal , petrol substances are called as fuel .
Ans .True
5) Acid rain is harmful for crop , soil , etc .
Ans .True
Q.3) Define the following
1) Combustion
Ans .A chemical process in which a substance reacts with oxygen to give off heat is called combustion.
2) Inflammable substance
Ans. The substance which have very low ignition temperature and can easily catch fire with a flame are called inflammable substances.
3) Explosion
Ans. A large amount of gas formed is liberated. Such reaction is called as explosion.
4) Calorific value
Ans. The amount of heat energy produced on complete combustion of 1 kg of a fuel is called its calorific value.
5) Acid rain
Ans. When oxides of Sulphur and nitrogen dissolve in rain water they form acid. Such rain is called acid rain.
Q.3) Answer the following
1) Write short note Global warming
Ans. Increased concentration of carbon dioxide in the air causes Global warming. These results in the melting of polar glaciers and leads to rise in sea level , causes floods in the coastal area.
2) What are three different types of combustion ?
Ans. Three different types of combustion are
- a) Rapid combustion
- b) Spontaneous combustion
- c) Explosion
3) Describe – Ideal fuel
Ans. Ideal fuel is cheap,readily combustible and easy to transport. It has high calorific value . There is no harm to the environment as it does not produce any harmful gases.
4) What is Acid rain ?
Ans. Whenever coal and diesel is burned it releases Sulphur dioxide. It is an corrosive gas. Such oxides of Sulphur and nitrogen dissolve in rain water and form acids. Such rain is called acid rain .These rain is harmful for soil, crop, building , etc.
Q.4) Write the calorific value of the following
1) Coal : 25000 – 33000
2) LPG : 55000
3) Biogas : 35000 – 40000
4) Kerosene : 45000
5) Wood : 17000 – 22000
Q.5) Match the following
Column A | Column B | Answer |
1) Coal | a) Gaseous fuel | Solid fuel |
2) Natural gas | b) Liquid fuel | Gaseous fuel |
3) Kerosene oil | c) Solid fuel | Liquid fuel |
In case you are missed :- NCERT Extra Questions for Conservation Of Plants And Animals