1. What is formed when hydrogen burns in oxygen?
A.
Water
B.
Carbon dioxide
C.
Nitrogen
D.
Ammonia
Correct Answer:
Water
Explanation:
Hydrogen combines with oxygen during combustion to form water.
2. What is the colour of the flame produced when hydrogen burns in air?
A.
Green
B.
Pale blue
C.
Bright yellow
D.
Red
Correct Answer:
Pale blue
Explanation:
Hydrogen burns in air with a pale blue flame.
3. Which gas is required for the combustion of hydrogen?
A.
Oxygen
B.
Nitrogen
C.
Carbon dioxide
D.
Helium
Correct Answer:
Oxygen
Explanation:
Oxygen supports the combustion of hydrogen and reacts with it to form water.
4. Which equation correctly represents the combustion of hydrogen?
A.
H2 + O2 → H2O
B.
2H2 + O2 → 2H2O
C.
H2 + O2 → H2O2
D.
2H2 + 2O2 → 2H2O
Correct Answer:
2H2 + O2 → 2H2O
Explanation:
The balanced combustion equation is 2H2 + O2 → 2H2O, showing that two molecules of hydrogen react with one molecule of oxygen.
5. What type of substance is hydrogen in its reaction with oxygen?
A.
Combustible gas
B.
Non-combustible solid
C.
Combustion-supporting gas
D.
Non-reactive liquid
Correct Answer:
Combustible gas
Explanation:
Hydrogen is combustible because it burns in oxygen.
6. What may happen when a mixture of hydrogen and oxygen is ignited?
A.
It freezes
B.
It explodes
C.
It becomes nitrogen
D.
It turns into carbon dioxide
Correct Answer:
It explodes
Explanation:
A mixture of hydrogen and oxygen can react explosively when ignited.
7. Which product can be condensed after hydrogen burns in oxygen?
A.
Water
B.
Sulfuric acid
C.
Methane
D.
Ammonia
Correct Answer:
Water
Explanation:
Combustion of hydrogen produces water, which can condense when cooled.
8. What is released during the combustion of hydrogen?
A.
Heat
B.
Only nitrogen
C.
Only carbon
D.
Chlorine gas
Correct Answer:
Heat
Explanation:
Hydrogen combustion is an exothermic reaction that releases heat.
9. Which gas does not burn but supports the combustion of hydrogen?
A.
Oxygen
B.
Hydrogen
C.
Methane
D.
Carbon monoxide
Correct Answer:
Oxygen
Explanation:
Oxygen supports hydrogen combustion, while hydrogen itself is the gas that burns.
10. What is the main visible sign that hydrogen is burning?
A.
A pale blue flame
B.
A black smoke cloud
C.
A green precipitate
D.
A white solid deposit
Correct Answer:
A pale blue flame
Explanation:
Burning hydrogen produces a characteristic pale blue flame.
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