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 the percentage of oxygen in the earth's atmosphere?

• 10%

• 15%

• 20%

• 25%

What is the effect of oxygen on a lighted splint?

• Oxygen extinguishes a lighted splint

• Oxygen makes a lighted splint burn even more

• Oxygen extinguishes a lighted splint with a pop sound

• Oxygen does not have any effect on a lighted splint

What is formed when copper reacts with oxygen?

• carbon dioxide and water

• carbon dioxide

• copper (II) oxide

• copper dioxide

Which of these gases are residual gases?

• Nitrogen

• Carbon dioxide

• Argon and Helium

• All

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

The change in this experiment is:

• A chemical change

• An oxidation reaction

• A synthesis reaction

• All three

Which gas (or gases) found in the earth atmosphere can be used for welding?

• Oxygen and argon

• Nitrogen

• nitrogen and water vapour

• water vapour

Which of these gases has a variable percentage in the air?

• Nitrogen

• Oxygen

• Carbon dioxide

• Water vapour