Which of the following examples involves an energy change of the system?

• A. A book sitting motionless on a table
• B. A glass of water at room temperature left undisturbed
• C. A chemical reaction in a beaker that releases heat to the surroundings
• D. A sealed container with no chemical or physical changes occurring

Answer: (C)

Verified step by step guidance

1. Understand the concept of 'energy change of the system': This refers to any process where the internal energy of the system changes, either by absorbing or releasing energy (such as heat or work).
2. Analyze each example to determine if the system undergoes an energy change:
3. 1. A book sitting motionless on a table: Since the book is not moving and no energy is being transferred, the system's energy remains constant.
4. 2. A glass of water at room temperature left undisturbed: No heat transfer or physical/chemical change occurs, so no energy change happens in the system.
5. 3. A chemical reaction in a beaker that releases heat to the surroundings: This involves a chemical change where energy is released from the system to the surroundings, indicating an energy change of the system.