physics : class11 Surface Energy per Unit Area : Surface Energy : Properties of Bulk Matter MCQ Questions and Answers
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Surface Energy per Unit Area
MCQ questions and answers.
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MCQ Questions
1. Surface energy per unit area is defined as the surface energy divided by the:
A.
Volume of the liquid
B.
Area of the surface
C.
Mass of the liquid
D.
Density of the liquid
Correct Answer:
Area of the surface
Explanation:
Surface energy per unit area is given by surface energy divided by the area of the surface.
2. What is the SI unit of surface energy per unit area?
A.
J m
B.
J/m²
C.
N m²
D.
kg/m³
Correct Answer:
J/m²
Explanation:
Surface energy is measured in joules and area in square metres, so surface energy per unit area has the SI unit J/m².
3. Surface energy per unit area is numerically equal to which quantity for a liquid surface?
A.
Pressure
B.
Surface tension
C.
Viscosity
D.
Density
Correct Answer:
Surface tension
Explanation:
For a liquid surface, surface energy per unit area is numerically equal to surface tension.
4. If the surface energy of a liquid surface is 6 J and its area is 3 m², what is its surface energy per unit area?
A.
2 J/m²
B.
3 J/m²
C.
9 J/m²
D.
18 J/m²
Correct Answer:
2 J/m²
Explanation:
Surface energy per unit area = surface energy/area = 6 J divided by 3 m² = 2 J/m².
5. Which expression represents surface energy per unit area?
A.
Area/surface energy
B.
Surface energy × area
C.
Surface energy/area
D.
Surface energy + area
Correct Answer:
Surface energy/area
Explanation:
By definition, surface energy per unit area is obtained by dividing surface energy by the surface area.
6. The unit N/m is equivalent to which unit for surface energy per unit area?
A.
J/m²
B.
J/m
C.
N·m
D.
N/m²
Correct Answer:
J/m²
Explanation:
Since 1 J = 1 N·m, N/m is equal to N·m/m², which is J/m².
7. A surface has a surface energy per unit area of 0.5 J/m². What is the surface energy of an area of 4 m²?
A.
0.125 J
B.
2 J
C.
4.5 J
D.
8 J
Correct Answer:
2 J
Explanation:
Surface energy = surface energy per unit area × area = 0.5 J/m² × 4 m² = 2 J.
8. If the surface energy remains unchanged while the surface area is doubled, the surface energy per unit area becomes:
A.
Doubled
B.
Halved
C.
Unchanged at twice its value
D.
Zero
Correct Answer:
Halved
Explanation:
Surface energy per unit area equals surface energy divided by area. If the same energy is spread over twice the area, its value becomes half.
9. A liquid surface has surface energy per unit area of 0.07 J/m². This value is also equal to its:
A.
Surface tension of 0.07 N/m
B.
Pressure of 0.07 Pa
C.
Density of 0.07 kg/m³
D.
Viscosity of 0.07 Pa·s
Correct Answer:
Surface tension of 0.07 N/m
Explanation:
Surface energy per unit area is numerically equal to surface tension, and J/m² is equivalent to N/m.
10. How much surface energy is required to create a surface area of 5 m² when the surface energy per unit area is 0.2 J/m²?
A.
0.04 J
B.
1 J
C.
2.5 J
D.
5.2 J
Correct Answer:
1 J
Explanation:
Surface energy = surface energy per unit area × area = 0.2 J/m² × 5 m² = 1 J.
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