Which type of change must occur to form a compound?

• A. A change in temperature only
• B. A chemical change
• C. A phase change
• D. A physical change

Answer: (B)

Verified step by step guidance

1. Understand the difference between physical and chemical changes: A physical change affects the form of a substance but not its chemical composition, such as changes in state (melting, boiling) or temperature.
2. Recognize that a phase change (like melting or boiling) and a change in temperature alone do not create new substances; they only alter the physical state or energy of the substance.
3. Define a chemical change as a process where substances react to form one or more new compounds with different chemical properties and compositions.
4. Identify that forming a compound requires breaking and forming chemical bonds, which is characteristic of a chemical change.
5. Conclude that to form a compound, a chemical change must occur, as this involves the rearrangement of atoms into new substances.