Surface Tension MCQs for NEET

Surface tension is the tendency of fluid surfaces to shrink into the minimum surface area possible. Intermolecular forces such as Van der Waals Force draw the liquid particles together. The ratio of the surface force F  to the length L along which the force acts.

T= F/L

Where,

• F is the force per unit length
• L is the length in which force act
• T is the surface tension of the liquid

Q1: When there are no external forces, the shape of a liquid drop is determined by

1. Surface Tension of the liquid
2. The density of the liquid
3. The viscosity of the liquid
4. The temperature of air only

Answer: (a) Surface Tension of the liquid

Q2: If T is the surface tension of the soap solution, the amount of work done in blowing a soap bubble from diameter D to a diameter 2D is

1. 2πD²T
2. 4πD²T
3. 6πD²T
4. 8πD²T

Answer: (c) 6πD²T

Q3: If the surface of a liquid is plane, then the angle of contact of the liquid with the walls of the container is

1. Acute angle
2. Obtuse angle
3. 90⁰
4. 0⁰

Answer: (d) 0⁰

Q4: Raindrops are spherical in shape because of

1. Capillary
2. Surface Tension
3. Downward motion
4. Acceleration due to gravity

Answer: (b)Surface Tension

Q5: In a surface tension experiment with a capillary tube, the water rises up to 0.1m. If the same experiment is repeated on an artificial satellite which is revolving around the earth. The rise of water in a capillary tube is

1. 0.1 m
2. 9.8 m
3. 0.98 m
4. Full length of the capillary tube

Answer: (d) Full length of the capillary tube

Q6: At the critical temperature, the surface tension of the liquid

1. Is zero
2. Is infinity
3. Is the same as that at the other temperature
4. Cannot be determined

Answer: (a) Is zero

Q7: The surface of the water in contact with the glass wall is

1. Plane
2. Concave
3. Convex
4. Both a and b

Answer: (b) Concave

Q8: When a soap bubble is charged

1. It contracts
2. It expands
3. It does not undergo any change in size
4. None of these

Answer: (b) It expands

Q9: If common salt is dissolved in water, then the surface tension of saltwater is

1. Increased
2. Decreased
3. Not changed
4. First increases then decrease

Answer: (a) Increased

Q10: A drop of oil is placed on the surface of the water. Which of the following statements is correct?

1. It will remain on it as a sphere
2. It will spread as a thin layer
3. It will partly be as spherical droplets and partly as thin films
4. It will float at the distorted drop on the water surface.

Answer: (b) It will spread as a thin layer

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