Cracker on ignition produces sound. Why?

Important Questions on Combustion and Flame

MEDIUM

8th CBSE

IMPORTANT

NCERT Exemplar Science - Class 8>Chapter 6 - Combustion and Flame>SHORT ANSWER QUESTIONS>Q 30

What do you understand by fuel efficiency?

EASY

8th CBSE

IMPORTANT

NCERT Exemplar Science - Class 8>Chapter 6 - Combustion and Flame>LONG ANSWER QUESTIONS>Q 31

 You are provided with three watch glasses containing milk, petrol and mustard oil, respectively. Suppose you bring a burning candle near these materials one by one, which material(s) will catch fire instantly and why?

MEDIUM

8th CBSE

IMPORTANT

NCERT Exemplar Science - Class 8>Chapter 6 - Combustion and Flame>LONG ANSWER QUESTIONS>Q 32

Manu was heating oil to fry potato chips. The cooking oil all of a sudden caught fire; he poured water to extinguish the fire. Do you think this action was suitable. If yes, why? If not, why not? In such a condition what should Manu have done?

MEDIUM

8th CBSE

IMPORTANT

NCERT Exemplar Science - Class 8>Chapter 6 - Combustion and Flame>LONG ANSWER QUESTIONS>Q 33

 What are the three essential requirements to produce fire? How fire extinguisher is useful for controlling the fire.

MEDIUM

8th CBSE

IMPORTANT

NCERT Exemplar Science - Class 8>Chapter 6 - Combustion and Flame>LONG ANSWER QUESTIONS>Q 34

Give two examples each for a solid, liquid and gaseous fuel along with some important uses.

MEDIUM

8th CBSE

IMPORTANT

NCERT Exemplar Science - Class 8>Chapter 6 - Combustion and Flame>LONG ANSWER QUESTIONS>Q 35

 The calorific values of petrol and CNG are$45000 \mathrm{kJ}/\mathrm{kg} \mathrm{and} 50,000 \mathrm{kJ}/\mathrm{kg}$, respectively. If you have vehicle which can run on petrol as well as CNG, which fuel will you prefer and why?

MEDIUM

8th CBSE

IMPORTANT

NCERT Exemplar Science - Class 8>Chapter 6 - Combustion and Flame>LONG ANSWER QUESTIONS>Q 36

 Although wood has a very high calorific value, we still discourage its use as a fuel. Explain.

HARD

8th CBSE

IMPORTANT

NCERT Exemplar Science - Class 8>Chapter 6 - Combustion and Flame>LONG ANSWER QUESTIONS>Q 37

Forest fire produces a lot of air pollution. Write in brief about the reasons of forest fires.