Understanding Oxygen and Nitrogen in the Atmosphere

The video explains that oxygen makes up about 1/5 of Earth's atmosphere, with nitrogen comprising most of the rest. Nitrogen is colorless, odorless, and unreactive. Liquid nitrogen, which must be handled carefully due to its low boiling point, can freeze objects and liquefy air. An experiment shows that liquid air can be separated into gases by boiling points, with nitrogen vaporizing first, leaving liquid oxygen. This separation is possible due to the different boiling points of oxygen and nitrogen.

What fraction of the Earth's atmosphere is composed of oxygen?

• 1/2

• 1/4

• 1/3

• 1/5

Which of the following is a property of nitrogen gas?

• Has a strong smell

• Colorless and odorless

• Highly reactive

• Green in color

What is one of the uses of liquid nitrogen?

• Producing electricity

• Creating fire

• Heating objects rapidly

• Freezing objects rapidly

What happens when a clean dry test-tube is dipped into liquid nitrogen?

• It melts

• It catches fire

• Liquid air forms

• It changes color

Which gas is left behind when nitrogen vaporizes first from liquid air?

• Hydrogen

• Oxygen

• Carbon dioxide

• Helium

Why can oxygen and nitrogen be separated from air?

• They are both colorless

• They have the same boiling points

• They have different boiling points

• They are both reactive