Common Gases Uses Competitive Exams
25 questions · Everyday Science
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Question 1 of 25
Which gas do plants release during photosynthesis?
ExplanationPlants take in CO2 and water and release oxygen in sunlight.
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Question 2 of 25
Carbon monoxide is poisonous because it:
ExplanationThis is why gas heaters should not be used in closed rooms.
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Question 3 of 25
Which gas do plants take in for photosynthesis?
ExplanationPlants use CO2 and water to make glucose in sunlight.
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Question 4 of 25
Carbon dioxide turns limewater:
ExplanationIt forms insoluble calcium carbonate, which makes the limewater cloudy.
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Question 5 of 25
A glowing splint relights when placed in which gas?
ExplanationThis is the standard test for oxygen; only oxygen can make the glowing splint burst into flame.
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Question 6 of 25
An oxy-acetylene torch used for welding and cutting metals burns acetylene in:
ExplanationThe flame reaches over 3000°C, hot enough to melt steel.
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Question 7 of 25
Which gas makes soft drinks fizzy?
ExplanationCO2 is dissolved under pressure and escapes as bubbles when the bottle is opened.
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Question 8 of 25
Which gas supports burning and is needed for respiration?
ExplanationFuels burn and our cells release energy from food using oxygen.
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Question 9 of 25
In the Haber process, ammonia is made from nitrogen and:
ExplanationN2 + 3H2 gives 2NH3 in the presence of an iron catalyst.
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Question 10 of 25
Oxygen cylinders in hospitals help patients who have difficulty in:
ExplanationPure oxygen helps patients with low oxygen levels in the blood.
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Question 11 of 25
A burning splint put in a test tube of hydrogen produces:
ExplanationHydrogen burns explosively with oxygen from the air, making a squeaky pop.
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Question 12 of 25
Which gas is used to fill party balloons because it is lighter than air and does not burn?
ExplanationHydrogen is also light, but it is flammable, so helium is safer.
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Question 13 of 25
Liquid nitrogen is mainly used to:
ExplanationNitrogen boils at about -196°C, which makes it a very strong coolant.
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Question 14 of 25
Dry ice is solid:
ExplanationDry ice changes directly into gas (sublimes) at about -78°C and is used to keep food cold.
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Question 15 of 25
Which gas released by burning sulphur-containing fuels causes acid rain?
ExplanationSO2 dissolves in rainwater to form acids that damage buildings, crops and lakes.
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Question 16 of 25
Which is the lightest gas?
ExplanationHydrogen is the lightest element; helium is the second lightest gas.
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Question 17 of 25
Which gas is used in fire extinguishers because it does not support burning and is heavier than air?
ExplanationCO2 covers the fire like a blanket and cuts off the supply of oxygen.
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Question 18 of 25
Neon gas in advertising signs gives which colour of light?
ExplanationOther colours in signs come from different gases or from coated tubes.
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Question 19 of 25
Packets of potato chips are often filled with which gas to keep them fresh?
ExplanationNitrogen is unreactive and prevents the oil in chips from reacting with oxygen and going stale.
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Question 20 of 25
The ozone layer protects life on Earth by absorbing:
ExplanationOzone in the stratosphere filters out most of the Sun's harmful UV rays.
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Question 21 of 25
Chlorine gas is used to:
ExplanationChlorine kills germs in water, but it is poisonous in large amounts.
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Question 22 of 25
Which gas makes up about 78% of the air we breathe?
ExplanationAir is about 78% nitrogen, 21% oxygen and small amounts of argon, carbon dioxide and other gases.
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Question 23 of 25
Which gas is filled in electric bulbs to prevent the filament from burning away?
ExplanationArgon is inert, so the hot tungsten filament does not react with it.
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Question 24 of 25
Ammonia is used mainly to make:
ExplanationPakistan produces a large amount of urea from ammonia for its farmers.
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Question 25 of 25
Nitrous oxide, known as laughing gas, is used in dentistry as:
ExplanationIt reduces pain and anxiety during minor procedures.
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