Combustion and Flame I - Concepts
Class - 8th ISO Subjects
Concept Explanation


A flame is a region where combustion of fuel takes place.

Substances which vapourise during burning produce flames. E.g. kerosene, wax etc. Substances which do not vapourise during burning do not produce flames. E.g. coal, charcoal etc. The colour of flame depends on: Temperature, amount of air available, nature of the substance burning.

      Luminous Flame

        Non Luminous Flame

  1. Give yellow flame

      1.  Give blue color flame

   2. Emits lot of light

     2.  Emit very little light

   3. Observed when there is insufficient oxygen

      or incomplete combustion

      3. Observed when there is sufficient amount 

       oxygen available

   4. Temperature is less and leaves behind black  soot and other residue.

    4. Leave no residues behind

Sample Questions
(More Questions for each concept available in Login)
Question : 1

Total amount of heat produced by a fuel having calorific value of 20 kJ/kg was found to be 50,000 Joules. How much fuel was burnt ?



Right Option : D
View Explanation
Question : 2

Flame produced due to incomplete combustion is called as ________________________

Right Option : A
View Explanation
Question : 3

Coal burns with __________

Right Option : B
View Explanation

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