Question

what happens when a fuel such as coal is heated to a high temperature in the presence of oxygen gas?
a energy is transferred from the oxygen to the coal.
b energy is released as heat which can then be used.
c energy is absorbed by the coal.
d energy is released as waste heat which cannot be used.

Explanation:

When coal (a fuel) reacts with oxygen (combustion), it is an exothermic reaction. In exothermic reactions, energy is released. This released energy can be harnessed and used (for example, to generate electricity in power plants). Option a is incorrect because in combustion, energy is not transferred from oxygen to coal. Option c is wrong as it's a release of energy not absorption. Option d is incorrect as the heat released in coal - oxygen combustion is not waste heat; it is utilized.

Answer:

B. Energy is released as heat which can then be used.