Question

Before thermal energy in fuel can be transferred to the air in heating systems, what has to occur? Its temperature must be raised by converting thermal energy to chemical energy. The energy in its chemical bonds must be converted to thermal energy. The kinetic energy must be stored in the chemical bonds of the fuel. Its temperature must be lowered to transfer energy from the air to the fuel.

Answer 1

i think its The energy in its chemical bonds must be converted to thermal energy

Step-by-step explanation:

Answer 2

Answer: The energy in its chemical bonds must be converted to thermal energy

Explanation: when fuel is burnt, the energy used to bind the molecules chemically are liberated as heat.