Combustion and Flame class 8th

What are Secondary fuels?

• Fuels that are used in the same form as they occur in nature.

• Fuels which are obtained from natural fuels after some chemical treatments.

• Fuels that are obtained from nature without any human interference.

• None of the above

Which fuel is used in our homes?

• Petrol

• Diesel

• Coal

• None of the above

Why acid rain is harmful?

• It damages forests.

• It affects marine life

• It cause damages to human and cause many diseases.

• All of the above

Which of the following is an ideal fuel?

• Kerosene

• Petrol

• CNG

• Diesel

Lighting up of LPG stove in the kitchen is the example of which type of combustion?

• Spontaneous combustion

• Rapid combustion

• Explosion

• None of the above

What is the ignition temperature of white phosphorus?

• 25°C

• 35°C

• 50°C

• 40°C

Complete combustion takes place in the presence of sufficient ________.

• Oxygen

• Carbon dioxide

• Hydrogen

• Carbon monoxide

What is ignition temperature?

• The lowest temperature at which a substance catches fire.

• The highest temperature at which a substance catches fire.

• The lowest temperature at which a substance will not catch fire.

• The highest temperature at which a substance will not catch fire.

By which of the following a huge fire caused by petrol can get extinguished easily and quickly?

• Water

• Fire extinguisher

• Sand

• Blanket

Which is the hottest zone of the candle flame?

☠️: Don't add 'The' in the beginning.