1. Water rises in a thin glass capillary tube because of
A.
Adhesion between water and glass
B.
Repulsion between water and glass
C.
Absence of surface tension
D.
Evaporation of water only
Correct Answer:
Adhesion between water and glass
Explanation:
Water wets glass because adhesive forces between water and glass are strong, causing water to rise in a narrow capillary tube.
2. When a capillary tube is dipped into mercury, mercury generally shows
A.
A rise in the tube
B.
A depression in the tube
C.
No change in level
D.
Complete evaporation
Correct Answer:
A depression in the tube
Explanation:
Mercury does not wet glass, so cohesive forces within mercury exceed adhesive forces with glass, producing capillary depression.
3. Which device uses capillary action to carry water from soil to the leaves of plants?
A.
Plant stems and narrow vessels
B.
Metal springs
C.
Glass mirrors
D.
Rubber balloons
Correct Answer:
Plant stems and narrow vessels
Explanation:
The narrow vessels in plant stems help water move upward by capillary action, assisted by adhesion and surface tension.
4. A kerosene lamp wick draws kerosene upward mainly due to
A.
Capillary action in the fine fibers
B.
Magnetic attraction
C.
Gravitational repulsion
D.
Boiling of kerosene
Correct Answer:
Capillary action in the fine fibers
Explanation:
The small spaces between the wick fibers act like capillary tubes and allow kerosene to rise to the flame.
5. For the same liquid, the height of capillary rise is greatest in a tube that is
A.
Very narrow
B.
Very wide
C.
Closed at both ends
D.
Made without an opening
Correct Answer:
Very narrow
Explanation:
Capillary rise increases as the radius of the tube decreases, so a very narrow tube gives a greater rise.
6. A blotting paper absorbs ink mainly because of
A.
Capillary action in its tiny pores
B.
The magnetic property of paper
C.
The boiling of ink
D.
The complete absence of surface tension
Correct Answer:
Capillary action in its tiny pores
Explanation:
The tiny pores in blotting paper act as capillaries and draw the ink into the paper.
7. If two capillary tubes of different radii are placed in water, water rises higher in the tube with
A.
The smaller radius
B.
The larger radius
C.
The thicker outer wall only
D.
No open end
Correct Answer:
The smaller radius
Explanation:
For a wetting liquid such as water in glass, capillary rise is inversely proportional to the radius of the tube.
8. The rise of oil through a lamp wick is an example of
A.
Capillary action
B.
Diffraction
C.
Electrolysis
D.
Sedimentation
Correct Answer:
Capillary action
Explanation:
Oil moves through the narrow spaces between wick fibers because these spaces act as capillary passages.
9. A liquid that wets the material of a capillary tube generally forms a
A.
Concave meniscus and rises
B.
Convex meniscus and rises
C.
Concave meniscus and depresses
D.
Flat meniscus and evaporates immediately
Correct Answer:
Concave meniscus and rises
Explanation:
A wetting liquid has stronger adhesive attraction to the tube, producing a concave meniscus and capillary rise.
10. Capillary tubes are used in thermometers because the liquid level
A.
Moves noticeably through the narrow tube
B.
Remains fixed at all temperatures
C.
Falls only due to gravity
D.
Turns into a solid immediately
Correct Answer:
Moves noticeably through the narrow tube
Explanation:
A small change in liquid volume produces a visible change in height in a narrow capillary tube, allowing temperature measurement.
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