The video explains that water (H2O) and rust (iron oxide) are examples of oxides. It highlights that the Earth's crust is predominantly composed of oxides, with silicon dioxide making up 60%, aluminum oxide 15%, and the remainder consisting of other metal oxides.

Which of the following is an example of an oxide?

• Carbon dioxide

• Ammonia

• Methane

• Water

What percentage of Earth's crust is made up of silicon dioxide?

• 30%

• 45%

• 60%

• 75%

Which of the following is the main component of sand and quartz?

• Silicon dioxide

• Aluminum oxide

• Iron oxide

• Calcium carbonate

What is the approximate percentage of aluminum oxide in Earth's crust?

• 25%

• 10%

• 15%

• 20%

Besides silicon and aluminum oxides, what else mainly composes Earth's crust?

• Organic compounds

• Other metal oxides

• Non-metallic elements

• Gaseous elements