Which of the following statements best describes whether a chemical reaction can occur with only one substance?

• A. No, a chemical reaction always requires at least two different substances to react.
• B. Yes, a chemical reaction can occur with only one substance if it undergoes decomposition or rearrangement.
• C. Yes, but only if the substance is an element.
• D. No, chemical reactions cannot occur without the presence of a catalyst.

Answer: (B)

Verified step by step guidance

1. Understand the nature of chemical reactions: A chemical reaction involves the breaking and forming of chemical bonds, resulting in the transformation of substances into new substances.
2. Recognize that a chemical reaction does not necessarily require two different substances; a single substance can undergo a chemical change by itself.
3. Consider examples such as decomposition reactions, where one compound breaks down into two or more simpler substances, or rearrangement reactions, where atoms within a molecule rearrange to form a different molecule.
4. Evaluate the given options: The statement that a chemical reaction can occur with only one substance if it undergoes decomposition or rearrangement correctly reflects this concept.
5. Conclude that the presence of multiple substances or a catalyst is not always necessary for a chemical reaction to occur; a single substance can react by itself under the right conditions.