extra questions answers of chapter 6 class 8th science
Answers
Answer:
Question 1.
Name the most common fuel used in homes.
Answer:
Liquefied Petroleum Gas. (LPG)
Question 2.
Name the most common fire extinguisher.
Answer:
Water
Question 3.
What are the states in which a fuel may exist?
Answer:
A fuql may exist in solid, liquid or gaseous state.
Question 4.
Name any two combustible substances.
Answer:
Charcoal, wood
Question 5.
Does magnesium produce heat and light during its combustion?
Answer:
Yes, it does.
Question 6.
What acts as a fuel for our body?
Answer:
Food
Question 7.
Give two examples of non-combustible substances. .
Answer:
Water, sand
Question 8.
How are heat and light produced in the sun?
Answer:
In the sun, heat and light are produced by nuclear reactions.
Question 9.
Where were matchsticks first used?
Answer:
Egypt
Question 10.
What are the three essential requirements for combustion?
Answer:
Fuel, air (to supply oxygen) and heat (to raise the temperature of the fuel beyond the ignition temperature).
Question 11.
What is the ignition temperature of phosphorus?
Answer:
25°C
Question 12.
What is the colour of an LPG flame?
Answer:
Blue
Question 13.
What type of process is combustion?
Answer:
A chemical process
Question 14.
Name an ideal fuel.
Answer:
Compressed Natural Gas (CNG)
Question 15.
What is the composition of the head of a matchstick?
Answer:
Antimony trisulphide and potassium chlorate.
Question 16.
Which part of a flame does a goldsmith blow for melting gold and silver?
Answer:
The goldsmith blows the outermost zone of a flame for melting gold and silver.
Question 17.
What is the unit for expressing the calorific value of a fuel?
Answer:
Kilojoules per kilogram (kJ/kg)
Question 18.
Comparing the calorific values of coal and petrol, state which fuel is better.
Answer:
The calorific value of coal is about 25,000 – 33,000 kJ/kg, whereas that of petrol is 45,000 kJ/kg. Hence, petrol is a better fuel.
Question 19.
What is deforestation?
Answer:
The cutting down of trees on a large scale is termed as deforestation.
Question 20.
Give any two examples of carbon fuels.
Answer:
Coal, petroleum
Combustion and Flame Class 8 Extra Questions Short Answer Questions
Question 1.
What does magnesium burn to form?
Answer:
Magnesium burns to form magnesium oxide and produces heat and light.
Question 2.
What does coal produce during its combustion?
Answer:
Explanation:
Answer:
Spontaneous combustion