chemistry : class11 Density : Properties of hydrogen : Hydrogen MCQ Questions and Answers
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Density
MCQ questions and answers.
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MCQ Questions
1. What is the approximate density of hydrogen gas at STP?
A.
0.09 g L⁻¹
B.
0.90 g L⁻¹
C.
9.00 g L⁻¹
D.
1.29 g L⁻¹
Correct Answer:
0.09 g L⁻¹
Explanation:
Hydrogen gas has an approximate density of 0.09 g L⁻¹ at STP, making it a very light gas.
2. Hydrogen is lighter than air because its density is:
A.
Greater than the density of air
B.
Equal to the density of air
C.
Less than the density of air
D.
Unrelated to the density of air
Correct Answer:
Less than the density of air
Explanation:
Hydrogen has a much lower density than air, so it is lighter than air.
3. The relative density of hydrogen with respect to oxygen is approximately:
A.
1
B.
2
C.
8
D.
1/16
Correct Answer:
1/16
Explanation:
At the same temperature and pressure, gas density is proportional to molar mass. Hydrogen has a molar mass of 2, while oxygen has a molar mass of 32, so the ratio is 2/32 = 1/16.
4. Which gas has a lower density than hydrogen at the same temperature and pressure?
A.
Oxygen
B.
Nitrogen
C.
Helium
D.
Carbon dioxide
Correct Answer:
Helium
Explanation:
Hydrogen is the least dense of the listed gases because its molar mass is 2, lower than the molar masses of helium, nitrogen, oxygen, and carbon dioxide.
5. At the same temperature and pressure, which factor mainly determines the density of a gas?
A.
Molar mass
B.
Colour
C.
Odour
D.
Flammability
Correct Answer:
Molar mass
Explanation:
For gases at the same temperature and pressure, density depends directly on molar mass. Hydrogen has a low density because its molar mass is very small.
6. If the density of air is approximately 1.29 g L⁻¹ at STP, how many times is hydrogen approximately lighter than air?
A.
About 2 times
B.
About 5 times
C.
About 14 times
D.
About 30 times
Correct Answer:
About 14 times
Explanation:
The ratio of the density of air to hydrogen is approximately 1.29/0.09, which is about 14. Thus, hydrogen is about 14 times lighter than air.
7. What happens to the density of hydrogen gas when its volume increases while its mass remains constant?
A.
It increases
B.
It decreases
C.
It remains exactly the same
D.
It becomes equal to the density of air
Correct Answer:
It decreases
Explanation:
Density is mass divided by volume. If mass remains constant and volume increases, the density of hydrogen decreases.
8. Which statement about the density of hydrogen gas is correct?
A.
Hydrogen is the heaviest gas
B.
Hydrogen has a very low density
C.
Hydrogen has the same density as oxygen
D.
Hydrogen is denser than carbon dioxide
Correct Answer:
Hydrogen has a very low density
Explanation:
Hydrogen has the lowest molar mass of common gases, so it possesses a very low density.
9. At the same temperature and pressure, the density of hydrogen gas compared with nitrogen gas is approximately:
A.
1:14
B.
14:1
C.
1:7
D.
7:1
Correct Answer:
1:14
Explanation:
Hydrogen has a molar mass of 2 and nitrogen has a molar mass of 28. Therefore, their density ratio is 2:28, which simplifies to 1:14.
10. Which property makes hydrogen suitable for filling balloons that need to rise in air?
A.
Its high density
B.
Its low density
C.
Its blue colour
D.
Its high boiling point
Correct Answer:
Its low density
Explanation:
Hydrogen has a density lower than that of air, so a hydrogen-filled balloon experiences upward buoyant force and rises.
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