Question

Ethene on combustion gives a _______ flame.

• A. yellow
• B. blue
• C. red
• D. green

Answer 1

The correct option is A yellow

Saturated hydrocarbons will generally give a clean flame while unsaturated carbon compounds will give a yellow flame with lots of black smoke.
Ethene $(C{H}_2=C{H}_2)$ is an unsaturated compound. In unsaturated hydrocarbons, the percentage composition of carbon is high and atmospheric oxygen is not enough to burn all the carbon present in it. Hence, unburnt carbon particles are present in the flame, making the flame sooty.