physics : class11 Capillary Action : Surface Tension : Properties of Bulk Matter MCQ Questions and Answers
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Capillary Action
MCQ questions and answers.
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MCQ Questions
1. The rise or fall of a liquid in a narrow tube is called:
A.
Capillary action
B.
Viscosity
C.
Buoyancy
D.
Diffusion
Correct Answer:
Capillary action
Explanation:
Capillary action is the rise or depression of a liquid in a narrow tube due to surface tension and adhesive forces.
2. Water rises in a clean glass capillary tube because:
A.
Adhesive force between water and glass is greater than cohesive force in water
B.
Cohesive force in water is greater than adhesive force with glass
C.
Water has no surface tension
D.
Glass pushes water upward mechanically
Correct Answer:
Adhesive force between water and glass is greater than cohesive force in water
Explanation:
Water wets glass because the adhesive attraction between water and glass is stronger than the cohesive attraction between water molecules, causing capillary rise.
3. Mercury is depressed in a glass capillary tube because:
A.
Adhesive force between mercury and glass is greater than cohesive force in mercury
B.
Cohesive force in mercury is greater than adhesive force between mercury and glass
C.
Mercury has zero surface tension
D.
Mercury evaporates inside the tube
Correct Answer:
Cohesive force in mercury is greater than adhesive force between mercury and glass
Explanation:
Mercury does not wet glass because its cohesive force is greater than its adhesive force with glass, producing capillary depression.
4. If the radius of a capillary tube is decreased, the height of capillary rise of a liquid generally:
A.
Increases
B.
Decreases
C.
Remains zero
D.
Becomes independent of the tube
Correct Answer:
Increases
Explanation:
The capillary rise is inversely proportional to the radius of the tube, so a narrower tube produces a greater rise.
5. In a capillary tube, the height of liquid rise is directly proportional to:
A.
Surface tension of the liquid
B.
Radius of the tube
C.
Density of the liquid only in the numerator
D.
Gravitational acceleration only in the numerator
Correct Answer:
Surface tension of the liquid
Explanation:
For capillary rise, h = 2T cosθ/(rρg), so the height is directly proportional to the surface tension T.
6. For a liquid that wets the walls of a capillary tube, the angle of contact is usually:
A.
Less than 90 degrees
B.
Exactly 90 degrees
C.
Greater than 90 degrees
D.
Always 180 degrees
Correct Answer:
Less than 90 degrees
Explanation:
A wetting liquid has an acute angle of contact, usually less than 90 degrees, allowing it to rise in the capillary.
7. The capillary rise of water becomes smaller when the tube is made wider because:
A.
Capillary rise is inversely proportional to the tube radius
B.
Surface tension becomes zero in a wider tube
C.
Water density becomes zero
D.
Adhesive forces disappear completely
Correct Answer:
Capillary rise is inversely proportional to the tube radius
Explanation:
According to the capillary-rise relation, h is proportional to 1/r, so increasing the tube radius reduces the height of rise.
8. Which of the following is an example of capillary action?
A.
Kerosene rising through the wick of a lamp
B.
A stone falling through air
C.
A ball rolling on the ground
D.
A metal block sinking in water
Correct Answer:
Kerosene rising through the wick of a lamp
Explanation:
The narrow spaces in a wick allow kerosene to rise through capillary action caused by surface tension and adhesive forces.
9. If a capillary tube is dipped in a liquid but the liquid does not wet the tube, the liquid level inside the tube will generally:
A.
Fall below the outside liquid level
B.
Rise above the outside liquid level
C.
Become exactly twice the outside level
D.
Remain unaffected in every case
Correct Answer:
Fall below the outside liquid level
Explanation:
A non-wetting liquid, such as mercury in glass, undergoes capillary depression and has a lower level inside the tube.
10. The capillary rise of a liquid is affected by the:
A.
Radius of the tube, surface tension, density, and angle of contact
B.
Colour of the tube only
C.
Mass of the capillary tube only
D.
Length of the tube only
Correct Answer:
Radius of the tube, surface tension, density, and angle of contact
Explanation:
The relation h = 2T cosθ/(rρg) shows that capillary rise depends on the tube radius, surface tension, angle of contact, and liquid density.
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