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Question

Naphthalene burns with a yellow sooty flame. This is because

The correct answer is

there is incomplete combustion

The correct answer is Option 2.

Key Points

Saturated hydrocarbons will generally give a clean flame, while unsaturated carbon compounds will give a yellow, sooty flame with a lot of black smoke.

Naphthalene is an unsaturated compound. The proportion of carbon in unsaturated hydrocarbons is higher than that in saturated hydrocarbons. That is, the carbon-to-hydrogen ratio is high.

As a result, some unburnt carbon particles are also formed during the combustion of unsaturated compounds.

In the flame, these unburnt hot carbon particles emit yellow light, which makes the flame appear yellow. Therefore, naphthalene burns with a yellow flame.

However, limiting the supply of air results in incomplete combustion of even saturated hydrocarbons, giving a sooty flame.

Therefore, the most appropriate reason for a yellow sooty flame is incomplete combustion.

The correct answer is Option (2).

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Important Questions from Hydrocarbons

  1. The number of structural isomers of pentane is 

  2. C 4H 8belongs to the homologous series of

  3. Refining of petroleum is carried out using which one of the following techniques?
  4. What is the number of mole(s) of H 2(g) required to saturate one mole benzene?

  5. Which one of the following carbon compounds will not give a sooty flame?

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