V. Short Answer Questions
1. What are the conditions necessary for combustion to take place?
2. It is difficult to burn a heap of green leaves, but dry leaves catch fire easily. Explain why.
3. Explain the reason why some substances burn with a flame.
4. Why does a goldsmith blow air into the kerosene lamp flame with a blowpipe?
5. What causes acid rain?
Answers
Answer:
1 . combustion is a burning a chemical natural basic process
Answer:
1 answer
Explanation:
Three things are required in proper combination before ignition and combustion can take place---Heat, Oxygen and Fuel. There must be Fuel to burn. There must be Air to supply oxygen. There must be Heat (ignition temperature) to start and continue the combustion process.
2nd answer:It is difficult to burn a heap of green leaves but dry leaves catch fire easily. ... The green leaves contain some water due to which the ignition temperature of leaves increases and they do not catch fire easily while dry leaves have no water, so they catch fire easily.
3rd answer:The substances which vaporize during burning produces flame. As these substances heat up, like candles, the rising C-atoms produce light. Heat produces light, which is known as incandescence. This causes formation of visible flame.
4th answer:Accepted Answer: A goldsmith blows air into the kerosene lamp flame with a blow pipe so that complete combustion of fuel takes place and the temperature of the flame increases. ... Otherwise the goldsmith blows the outermost, hotter zone of the flame on the jewellery.
5th answer:Acid rain is caused by a chemical reaction that begins when compounds like sulfur dioxide and nitrogen oxides are released into the air. These substances can rise very high into the atmosphere, where they mix and react with water, oxygen, and other chemicals to form more acidic pollutants, known as acid rain.