Which of the following statements about energy usage is correct?

• A. Potential energy is always greater than kinetic energy in any system.
• B. Energy can be created or destroyed in chemical reactions.
• C. Energy can be converted from one form to another, but the total energy of an isolated system remains constant.
• D. Heat and work are both forms of matter.

Answer: (C)

Verified step by step guidance

1. Step 1: Understand the Law of Conservation of Energy, which states that energy cannot be created or destroyed, only transformed from one form to another within an isolated system.
2. Step 2: Analyze the first statement: 'Potential energy is always greater than kinetic energy in any system.' This is not necessarily true because the relative amounts of potential and kinetic energy depend on the system's state and conditions.
3. Step 3: Evaluate the second statement: 'Energy can be created or destroyed in chemical reactions.' According to the conservation of energy, this is false; energy is conserved during chemical reactions.
4. Step 4: Consider the third statement: 'Energy can be converted from one form to another, but the total energy of an isolated system remains constant.' This aligns with the first law of thermodynamics and is correct.
5. Step 5: Review the fourth statement: 'Heat and work are both forms of matter.' This is incorrect because heat and work are forms of energy transfer, not matter.