The percentage of oxygen in the air

Which gas is the most abundant in the earth's atmosphere?

• Nitrogen

• Oxygen

• Carbon dioxide

• Helium

What is formed when copper reacts with oxygen?

• carbon dioxide and water

• carbon dioxide

• copper (II) oxide

• copper dioxide

The percentage of oxygen in the atmosphere is 20%.

How many cm3 of oxygen would you find in 50 cm3 of air?

• 5 cm3

• 10 cm3

• 15 cm3

• 20 cm3

In the experiment shown above, when should we stop passing the air in the syringe back and forth over the heated copper?

• When all the copper turns black

• When the volume of air remains the same in the syringes

• When the copper glows inside the tube

• We just pass it 6 times back and forth

Why does the copper turn black in this experiment?

• It has burnt to form a new product

• It has reacted with the air to from a new product

• It has reacted with the oxygen to form a new product

• It has decomposed to form a new product

What is the percentage of oxygen gas in air?

• %78

• %32

• %18

• %21

What is the laboratory test for Oxygen?

• Puts out a glowing splint

• Makes a squeaky pop sound with a burning splint

• Relights a glowing splint

What two things cause Iron to Rust ?

• Air and Oxygen

• Water and Carbon dioxide

• Oxygen and Water

• Carbon dioxide and Air

In an experiment, iron wool is put at the bottom of a test tube which is then inverted in a trough of water. The tube is left like this for a week. Explain what happens to the water.

Iron reacts to form rust. Complete the word equation for this reaction:

Iron + (a)   --> Rust