Tag: flame

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Questions Related to flame

Multiple choice chemistry combustion structure of flame flame combustion, fuels and flame

Artificial rubies and sapphires can be made by heating alumina in ?

  1. An oxy-hydrogen flame

  2. An oxy-acetylene flame

  3. Burning methane

  4. An electric furnace
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Artificial ruby and sapphires are manufactured from alumina to which 1.5% of magnetic iron oxide and 0.5% of titanium oxide has been added, the mixture is fused and crystallised in an oxy-hydrogen flame. It is a reducing flame.

Multiple choice chemistry combustion structure of flame flame combustion, fuels and flame

A lilac-coloured flame is produced on heating.

  1. Potassium in a flame

  2. Cobalt in a flame

  3. Sodium in a flame

  4. Methane in oxygen
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation
Potassium on heating produced lilac-colured flame because on heating, an atom entities its electrons and they jump to higher energy levels. When the electron return to lower energy levels, they emit energy in the form of light. The colour produced on heating depends upon wavelength of emitted light.
Multiple choice chemistry combustion structure of flame flame combustion, fuels and flame

If you watch a burning candle carefully, you will find different colurs in the flame. Which is the hottest part of the candle flame?

  1. The middle orange part

  2. The middle, yellow part

  3. The outermost portion that is blue

  4. The innermost black zone
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

The outermost portion that is blue.

The hottest part of the candle flame is the blue part, at $1670^oF$ ($1400^oC$) i.e., the outermost portion, where the flame has the most oxygen and you are getting complete combustion.

Multiple choice chemistry combustion structure of flame flame combustion, fuels and flame

The flame of the candle has three zones. The outer zone is blue, the middle zone is yellow and the inner zone is black. Which is correct regarding this?

  1. The outer zone is hottest hot.

  2. The middle zone is hottest

  3. The inner zone is least hot

  4. All the zones have same temperature
Reveal answer Fill a bubble to check yourself
A,C Correct answer
Explanation

Candles produce light by releasing heat. A candle flame consists of three zones. Each zone has different temperatures and colors.

  • The first zone is called the Outer zone
  • The second zone is called the Middle zone
  • The third zone is called the Inner zone

The outer zone is blue in color, due to complete combustion,. This zone is the hottest zone.

The middle one is in yellow color, which is the bright part of the flame. It is moderately hot and partial combustion of fuel takes place.

The least hot region of the flame is innermost zone. This inner zone is black in color due to the presence of unburnt wax vapors.

Multiple choice chemistry combustion and flame structure of flame flame combustion

What is the maximum possible temperature( in $^0 C$) of a Bunsen burner flame? Assume that the gas is pure methane and that it is pre-mixed with sufficient air to permit complete combustion.

  1. 1500

  2. 4000

  3. 5000

  4. 1100
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

The adiabatic flame temperature of a methane-air flame is approximately 1900-2000 degrees Celsius. Among the provided options, 1500 is the most reasonable estimate for a standard Bunsen burner flame, as heat losses prevent it from reaching the theoretical maximum.

Multiple choice chemistry combustion and flame structure of flame flame combustion

Burning of coal and wood causes  _____________.

  1. pollution of air

  2. decrease of non-renewable source of energy

  3. both (a) and (b)

  4. neither (a) or (b).
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Burning of coal and wood causes air pollution and because of burning of coal and wood there is decrease in amount of non-renewable sources. 

Multiple choice chemistry combustion and flame structure of flame flame combustion

The zone of no combustion is _______.

  1. The middle zone

  2. Outermost zone

  3. The base of the flame

  4. Innermost zone
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Innermost zone is the zone of no combustion. It is also called as dark zone which is formed around the wick of the candle flame.

Multiple choice chemistry combustion and flame structure of flame flame combustion

Substance which vaporize during burning gives ____________.

  1. sound

  2. flame

  3. combustion

  4. none of these
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Substances which vaporize during burning gives flame. For example, combustion of kerosene oil produces a flame. On the other hand, certain substances like coal do not vaporize and hence does not produce a flame.