Question

lesson 24: systems and energy
which of the following is due to a flow of energy?
chemical changes
phase changes
chemical reactions
freezing

Explanation:

• Chemical changes involve the breaking and forming of chemical bonds, which requires energy flow.
• Phase changes (like freezing) involve energy transfer (e.g., heat loss in freezing).
• Chemical reactions are a type of chemical change and thus involve energy flow.

Answer:

All of the options (chemical changes, phase changes, chemical reactions, freezing) are due to a flow of energy.