Air
Chemistry · 50 practice questions
Natural gaseous constituents of air and their proportions — nitrogen, oxygen, water vapour, carbon(IV) oxide and the noble gases (argon, neon); air as a mixture and uses of the noble gases.
- Deduce reasons for the existence of air as a mixture.
- Identify the principle involved in separating air's components.
- Deduce reasons for variation in air composition in the environment.
- Specify the uses of some of air's constituents.
Try a few questions
- Practice question 1
In the candle-and-water-jar experiment, the water typically rises to occupy approximately
- A.all of the original volume of air, since every gas present is consumed
- B.exactly half of the original volume of air
- C.none of the original volume of air at all
- D.one-fifth of the original volume of air, consistent with the roughly 21% oxygen content of air
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D. one-fifth of the original volume of air, consistent with the roughly 21% oxygen content of air
The rising water volume closely matches the fraction of air that was oxygen and got consumed by combustion.
- Practice question 2
Nitrogen's main use as an inert atmosphere, such as in food packaging, is mainly to
- A.actively promote the oxidation of packaged food
- B.increase the rate at which food spoils
- C.add a distinctive flavour to the packaged food
- D.prevent the oxidation of easily oxidized substances
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D. prevent the oxidation of easily oxidized substances
Nitrogen's chemical inertness lets it displace oxygen, protecting the packaged contents from oxidative spoilage.
- Practice question 3
The amount of water vapour present in the air mainly varies due to
- A.the fixed, unchanging composition of nitrogen in air
- B.local humidity and weather conditions
- C.the exact altitude of sea level everywhere
- D.the constant proportion of noble gases present
Show the answer
B. local humidity and weather conditions
Humidity and weather directly influence how much water vapour the air holds at a given time and place.
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