Question

During combustion of gaseous fuels, deficiency of air ___________.

• A. Lengthens the flame.
• B. Tends to shorten the flame.
• C. Does not affect the flame length.
• D. Increases the flame temperature.

Answer 1

The correct option is A Lengthens the flame.

During combustion of gaseous fuels, deficiency of air lengthens the flame. When combustion is carried out in limited supply of air, the combustion is incomplete. The products of combustion remain unburnt and contaminate the smoke with particulate matter. Hence, the length of the flame increases.