Question

question 6 (4 points) saved
the cas registry number is
is usually fatal
always has a sudden effect
is characterized by repeated exposure over months or years.
a unique identifying number for each chemical

Explanation:

CAS registry numbers are standardized identifiers assigned by the Chemical Abstracts Service to every chemical substance, ensuring each has a unique, consistent label for identification across contexts. The other options describe toxic exposure effects, not the CAS number itself.

Answer:

a unique identifying number for each chemical