Which of the following best explains the energy transformation that occurs in hydrogen fuel cells?

• A. Thermal energy is directly converted into mechanical energy.
• B. Light energy is absorbed and converted into chemical energy.
• C. Electrical energy is used to split water into hydrogen and oxygen gases.
• D. Chemical energy in hydrogen is converted to electrical energy through a redox reaction.

Answer: (D)

Verified step by step guidance

1. Understand that a hydrogen fuel cell converts chemical energy stored in hydrogen into electrical energy through an electrochemical process.
2. Recognize that in a hydrogen fuel cell, hydrogen gas undergoes oxidation at the anode, releasing electrons and producing protons.
3. Know that oxygen gas undergoes reduction at the cathode, where it combines with electrons and protons to form water.
4. Identify that the flow of electrons from the anode to the cathode through an external circuit generates electrical energy.
5. Conclude that the overall energy transformation in a hydrogen fuel cell is the conversion of chemical energy in hydrogen into electrical energy via redox reactions.