What type of energy transformation takes place when carbon is cycled in a gasoline-based car? A) Thermal energy to thermal energy B) Chemical energy to chemical energy C) Thermal energy to mechanical energy D) Chemical energy to mechanical energy

What this question is really asking

You are tracking what form of energy the fuel starts with, and what useful form of energy the car produces for motion.

Where the starting energy comes from

Gasoline is made of hydrocarbons, so its energy is stored in chemical bonds. When the fuel burns with $O_2$, those bonds rearrange to form $CO_2$ and $H_2O$, releasing energy.

What the car turns that energy into

Combustion heats gases in the engine, the hot expanding gases push pistons, and that force produces motion of the crankshaft and wheels. The “output” energy for moving the car is mechanical energy (work).

Why choice D is the best match (and why the others are not)

• D is correct: chemical energy in gasoline  mechanical energy of moving engine parts and the car.
• A is wrong because the output is not just heat.
• B is wrong because the main useful conversion is not chemical to chemical; chemical reactions happen, but the key transformation asked is into motion.
• C is wrong because the energy source is not thermal to begin with; it starts as chemical energy in the fuel.

Quick reality check

Some energy does become thermal (waste heat, exhaust), but the key transformation that powers the car’s motion is chemical  mechanical.