Question

1. which atomic window best represents a pure substance? 2. the air we breathe is composed of about 20% oxygen gas o₂(g) and 80% nitrogen gas n₂(g). which atomic window below best represents air? a. b. c. d.

Explanation:

Step1: Recall definition of pure substance

A pure substance has only one - type of particle.

Step2: Analyze each option

• Option a: Shows a mixture of single - atoms.
• Option b: Shows a compound (a combination of different atoms).
• Option c: Shows a mixture of di - atomic molecules of different elements.
• Option d: Shows only nitrogen di - atomic molecules, which is a pure substance as it has only one type of molecule.

Step3: Recall composition of air

Air is a mixture of about 20% oxygen gas ($O_2$) and 80% nitrogen gas ($N_2$). Option c shows a mixture of oxygen and nitrogen di - atomic molecules, representing air.

Answer:

1. d
2. c