Compounds involve which type of change?

• A. Physical
• B. Nuclear
• C. Chemical
• D. Electrical

Answer: (C)

Forming a compound is a chemical change because it involves making and breaking chemical bonds to produce a substance with new properties that are different from the starting elements. When elements combine, their atoms rearrange into a new, fixed ratio and structure, creating a compound with its own chemical identity. For example, hydrogen and chlorine react to form hydrogen chloride, a substance with properties that none of the original gases had. This change can't be reversed by simple physical means; you'd typically need another chemical process to break the bonds and recover the original elements.

Physical changes, by contrast, only affect appearance, state, or form without creating a new substance, so the material’s identity remains the same. Nuclear changes involve the nucleus of atoms and are about altering the identity of elements at a fundamental level, not about forming compounds through bonding.