Composition of Air

How many percent of oxygen is present in the air

• 20%

• 21%

• 78%

• 50%

This gas makes up 0.04% of air.

• carbon dioxide

• nitrogen

• oxygen

• water vapor

How much Nitrogen is in the atmosphere?

• 78%

• 21%

• 100%

• 1%

At what temperature does nitrogen boil at atmospheric pressure?

• -196°C

• -183°C

• -273°C

• 0°C

Which gas is commonly removed from air by passing it through a solution of potassium hydroxide (KOH)?

• Nitrogen

• Oxygen

• • Carbon dioxide

• Argon

What is the role of limewater (Ca(OH)₂) in testing for the presence of carbon dioxide?

• It turns blue

• It turns milky

• It releases oxygen

• It absorbs nitrogen

Which gas, when passed through a solution of alkaline pyrogallol, is absorbed?

• Nitrogen

• Oxygen

• • Carbon dioxide

• Argon

In the separation of air using solutions, which gas is usually the least reactive and therefore hardest to separate?

• Nitrogen

• Oxygen

• Carbon dioxide

• Argon

Which component of air can be removed by passing air through concentrated sulfuric acid (H2SO4)?

• Water vapor

• Nitrogen

• Oxygen

• Argon

What is the role of a fractional distillation column in the separation of air?

• To absorb impurities

• To provide a large surface area for condensation and evaporation

• To filter out solids

• To regulate the temperature