which of these is a compound? o o o co2 o o2 o co

Answer:

B. $CO_2$

Explanation:

Step1: Define a compound

A compound is a substance made of two or more different - element atoms chemically combined.

Step2: Analyze each option

• Option A: 'O' represents an oxygen atom, not a compound.
• Option B: $CO_2$ is carbon dioxide. It is made of one carbon atom and two oxygen atoms chemically bonded, so it is a compound.
• Option C: $O_2$ is an oxygen molecule composed of two oxygen atoms of the same element, so it is an element (a di - atomic molecule of an element), not a compound.
• Option D: 'Co' represents the element cobalt, not a compound.