Answer: Some of the chemical energy in natural gas transforms into thermal energy, which heats the water. Then some of the thermal energy changes into sound energy when the water forms steam and the steam leaves the kettle.
Step-by-step explanation:
The natural gas consists of chemicals, which when burn produces thermal energy. This thermal energy is utilized for heating or boiling water. The boiling water produces steam the steam tries to come out of the kettle thus makes sound over the kettle lid, the pressure created by steam while leaving kettle produces sound energy.