According to the law of conservation of energy, energy can:

• A. Energy can neither be created nor destroyed, but can be converted from one form to another
• B. Energy is conserved but can only be transformed into heat
• C. Energy is always increasing in a closed system
• D. Energy is never transformed between forms

Answer: (A)

The concept being tested is that energy in a closed system cannot be created or destroyed; it can only change form. This is the essence of the conservation of energy—the total amount of energy stays the same even as it shifts from one type to another.

The statement that energy cannot be created or destroyed, but can be converted from one form to another matches this idea exactly. In real life, energy moves around all the time in different forms: a falling object converts gravitational potential energy into kinetic energy; a light bulb turns electrical energy into light and thermal energy; a swinging pendulum trades kinetic and potential energy back and forth. The total amount of energy remains constant even as the forms change.

The other ideas don’t fit because they impose limits or deny transformations. Energy being conserved only as heat ignores all other forms energy can take. Saying energy in a closed system always increases conflicts with the idea that energy is conserved. And claiming energy is never transformed between forms contradicts the many observable conversions that occur every day.