What type of information is typically found in a Chemical Abstracts Service (CAS) registry number?

The correct answer highlights that a Chemical Abstracts Service (CAS) registry number is primarily used for substance identification. Each unique CAS number serves as a unique identifier for a specific chemical substance, allowing for precise tracking and referencing. This identification is critical in scientific, regulatory, and industry contexts, as it enables users to differentiate between chemicals with similar names or properties.

While chemical structures, common uses, and toxicological data might be related to the substance identified by the CAS number, they are not directly provided by the CAS number itself. Instead, the CAS registry number functions purely as a unique identifier to ensure that the specific chemical can be accurately referenced across various databases and literature.