Answer: C
There are 2 or more different type of atoms within a molecule
I would say you should use or test it once a week to ensure it is working properly in an active laboratory since it is a workplace with significant chemical hazards so it would give peace of mind to know on a quite regular basis that it can be relied on in case of an emergency like an eye flush for example.
Answer:
B
Explanation:
Heating a piece of iron until it glows.