Question

Combustion of a substance releases heat and ___.

• A. water
• B. light
• C. wood
• D. oxygen

Answer 1

The correct option is B light

Combustion or burning is a chemical process in which a substance reacts with oxygen to give off heat and light. Light is either in the form of a glow or a flame. Not all substances have a flame when burned. Flame depends on whether or not combustible vapours are released by the fuel.

An example of combustion without a flame is the burning of coal. An example of combustion with a flame is a burning candle.