What is the colour of the flame when unsaturated hydrocarbons burn?

Correct option is D

The correct answer is (d) Yellow.
 Unsaturated hydrocarbons, such as alkenes and alkynes, burn with a yellow flame.
 This yellow flame is due to incomplete combustion, which results in the formation of carbon particles (soot) that glow yellow when heated.
 The presence of these carbon particles makes the flame appear luminous and yellow.
 Incomplete combustion occurs because unsaturated hydrocarbons have a higher carbon content and require more oxygen to burn completely, which is often not available in sufficient quantity during the combustion process.
Information Booster:
 Blue Flame:
o A blue flame typically indicates complete combustion, commonly seen when saturated hydrocarbons (like methane) burn.
o The blue color is due to the high temperature and complete oxidation of the fuel.
 Red Flame:
o A red flame is usually observed at lower temperatures and indicates the presence of specific metal salts or incomplete combustion under certain conditions.
o It is not characteristic of the burning of hydrocarbons.
 Green Flame:
o A green flame is typically produced by the presence of certain elements like boron or copper in the combustion process.
o It is not associated with the combustion of hydrocarbons.