Structure of Flame

Q. The burning in the innermost region of a flame around the wick is very less and the region majorly has unburnt wax vapour.

1. Blue zone

2. Veil

Q.

Describe a flame

Q.

The wax in the upper part of a candle melts because -

1. All of these
2. It absorbs some energy from the flame.
3. It releases energy to the surroundings.
4. Wax melts due to low pressure created by flame.

Q.

Give an explanatory diagram of candle flame. [3 MARKS]

Q.

The flame of a candle is always upright due to ___________.

1. Convection

2. Conduction

3. Oxygenation

4. Combination

Q.

The flame of a candle is always upright due to ___________.

1. Convection

2. Chemical energy

3. Air drag

4. Conduction

Q.

In a candle, the process of burning continues because:

1. The wick keeps delivering molten wax to the flame.

2. The wick keeps burning.

3. Solid wax keeps burning.
4. Sufficient heat energy is available.

Q.

The movement of molecules close to a source of heat away from it and of those molecules which are away from the source of heat towards the source is called ____________.

1. Convection

2. Diffusion

3. Conduction

4. Explosion

Q. Whenever there is a fire, the flame is always in the upward direction.

1. Condensation

2. Combustion

Q. Abida and Ramesh were doing an experiment in which water was to be heated in a beaker. Abida kept the beaker near the wick in the yellow part of the candle flame. Ramesh kept the beaker in the outermost part of the flame. Whose water will get heated in a shorter time?

Q.

The shape of a flame inside a space shuttle when there is no gravity will be _______.

1. Evaporation

2. Diffusion

3. Convection

4. Condensation

Q. Which of the following happen when a wax candle is burnt

1. (i) and (ii) only
2. (ii) and (iii) only
3. (iii) and (i) only
4. (i), (ii) and (iii)

Q. Which of the following is a false description about different zones of a flame ?

1. $W$- It is non-luminous, the hottest part and contains unburnt carbon particles.
2. $X$- It is luminous and involves partial combustion.
3. $Y$- It is least hot and dark.
4. $Z$- It is blue zone where carbon monoxide burns.

Q.

The moving away of molecules close to a source of heat and of those molecules which are away from the source of heat towards the source is called ____________.

1. Convection

2. Diffusion

3. Explosion

4. Conduction

Q.

The moving away of molecules close to a source of heat and of those molecules which are away from the source of heat towards the source is called ____________.

1. Explosion

2. Conduction

3. Convection

4. Diffusion

Q. Which of the following cannot be classified as a particulate matter?

1. Nitrogen
2. Soot
3. Smoke
4. Dirt

Q. When you tilt a burning candle, the flame will -

1. Either stay upright or tilt to the side
2. The flame will go off
3. Tilt to the side
4. Stay upright

Q.

The shape of a flame inside a space shuttle when there is no gravity will be _______.

1. spherical

2. like a teardrop

3. conical

4. like a kidney bean

Q. Abida and Ramesh were doing an experiment in which water was to be heated in a beaker. Abida kept the beaker near the wick in the yellow part of the candle flame. Ramesh kept the beaker in the outermost part of the flame. Whose water will get heated in a shorter time?
[2 marks]
[NCERT Q.13]
[Zones of candle flame]

Q.

What change do you expect in the flame of the candle as shown in the figure? Explain.

Q. When you tilt a burning candle, the flame will:

1. Tilt to the side
2. Stay upright
3. Either stay upright or tilt to the side
4. The flame will go off

Q.

The flame of a candle is always upright due to ___________.

1. Conduction

2. Oxygenation

3. Convection

4. Combination

Q. Abida and Ramesh were doing an experiment in which water was to be heated in a beaker. Abida kept the beaker near the wick in the yellow part of the candle flame. Ramesh kept the beaker in the outermost part of the flame. Whose water will get heated in a shorter time?