Combustion

1. What is the colour of middle zone of flame? What happens in the middle zone of flame?
2. Which is the hottest part of the flame?
What is the end product of combustion in this zone?
3. Write an experiment to show that wax vapours are present in innermost zone of candle flame.
4. When you put a glass slide over a candle flame grey ring is seen on the outer surface. Why?
5. A long copper wire put across a candle flame becomes red in non luminous part of the flame. Why?
6. What is calorific value of a fuel? Write it's unit also.
7. Write 4 characteristics of a good fuel.

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