Candle Flame

Q. Why do goldsmith blow the outermost zone of the flame?

Q.

What are the necessary conditions for a fire to start? How can the fire be put off if required? [5 MARKS]

Q. The outermost region of a flame is the zone of complete combustion.

1. True
2. False

Q. In a flame given by a candle complete combustion takes place in the outer most part and then in the middle part there is incomplete combustion but when oxygen is present everywhere then why is it that in one part there is complete combustion and in the other not?

Q. The innermost region of a candle flame has the lowest temperature.

1. True
2. False

Q. Question 24
Match the following for the flame of a candle.

Q.

Which of the following factors are essential to ignite a fire?

1. Heat

2. Air (oxygen)

3. Fuel

4. All of these

Q. _______ colour zone of a candle flame is used by a goldsmith for melting gold and silver.

1. Blue
2. Black
3. Yellow
4. White

Q.

Which of the following should be done to control fire?

1. Reduce the heat supply

2. Increase fuel supply

3. Increase the oxygen supply

4. Reduce the nitrogen supply

Q. The different zones of a candle flame are marked by the letters A, B and C.


Which of the following is correct with respect to the zones of the candle?

1. Zone A is the hottest part of the flame.
2. Zone B is moderately hot.
3. Zone B is the hottest part of the flame.
4. Zone C is moderately hot.

Q. Fill in the blanks in the following sentences.​
(a) A ____________ process in which a substance reacts with__________ to give off heat is called combustion.​
(b) When the clothes of a person catch __________, the person is covered with a __________ to extinguish fire.
(c) The __________ temperature at which a substance catches fire is called its __________ temperature.
(d) The substances which have very ________________ ignition temperature and can easily catch fire with a flame are called__________ substances.
(e) The substances which vapourise during __________, give flame.​

Q. The outermost zone is the hottest part of a candle flame.

1. True
2. False

Q. The outermost zone is the hottest part of a candle flame.

1. False
2. True

Q. Which of the following is not a component of a fire triangle?

1. Oxygen
2. Nitrogen
3. Fuel
4. Heat

Q. Make a labelled diagram of a candle flame.

Q. Which among the following does not produce a flame on burning?

1. Kerosene oil
2. Candle
3. Plastic
4. Camphor

Q. Match the following for the flame of a candle.

Q. Match the following for the flame of a candle.

Q. Partial combustion takes place in the middle region of a candle flame. The temperature of this region is ________.

1. lower than inner region
2. higher than inner region
3. lower than outer region
4. higher than outer region

Q. Make a labelled diagram of a candle flame.

Q. Make a labelled diagram of a candle flame.

Q. Question 26
Fill in the blanks using the words given in the box.

(a) A chemical process in which a substance reacts with oxygen to give off heat is called ___
(b) Wood, paper, CNG are ___ substances.
(c) The lowest temperature at which a substance catches fire is called its ___ temperature.
(d) Ignition temperature of ___ is lower than that of wood.
(e) The substances which have very low ___ temperature and can easily catch fire with a flame are called ___ substances.
(f) The amount of heat energy produced on complete combustion of 1kg of a fuel is called its ___.

Q. The colour of the outer zone of a candle flame is _________.

1. red
2. blue
3. orange
4. yellow

Q. Match the different color shown by different zones of a candle flame.

1. Black
2. Yellow
3. Blue

Q. The outermost zone is the hottest part of a candle flame.

1. True
2. False

Q. Statement I: Fire can be stopped by cutting off the oxygen supply.
Statement II: A substance cannot catch fire in the absence of oxygen.

1. Only statement I is true
2. Only statement II is true
3. Both statements are true
4. Both statements are false

Q. The outermost region of the flame have the temperature.

1. moderate
2. highest
3. lowest

Q. The middle part of the flame undergoes partial combustion.

1. False
2. True

Q. Explain how CO2 is able to control fires.

Q. The outermost region of the flame have the temperature.

1. highest
2. lowest
3. moderate