Q. A capillary tube is dipped in water. What is the shape of the water surface inside the tube?
A.
Flat
B.
Concave
C.
Convex
D.
Irregular
Solution
The water surface inside the capillary tube is concave due to the adhesive forces between water and the tube material being stronger than the cohesive forces among water molecules.
Q. A capillary tube is dipped into water. How high will the water rise in the tube if the radius is 1 mm?
A.
2.5 cm
B.
5 cm
C.
10 cm
D.
15 cm
Solution
Using the capillary rise formula, h = (2γcosθ)/(ρgr), where γ is surface tension, θ is contact angle, ρ is density, g is acceleration due to gravity, and r is radius.
Q. A capillary tube is dipped into water. The height to which water rises in the tube is determined by:
A.
Surface tension and density of the liquid
B.
Only surface tension
C.
Only density of the liquid
D.
Viscosity of the liquid
Solution
The height of the liquid column in a capillary tube is determined by both surface tension and the density of the liquid, as described by the capillary rise formula.
Correct Answer:
A
— Surface tension and density of the liquid
Q. A capillary tube is dipped into water. The water rises in the tube due to which of the following?
A.
Surface tension and adhesion
B.
Surface tension and cohesion
C.
Only adhesion
D.
Only cohesion
Solution
The rise of water in a capillary tube is due to both surface tension (which pulls the liquid up) and adhesion (the attraction between water molecules and the tube's surface).
Q. A capillary tube of radius 0.5 mm is dipped in water. What is the height of the water column raised in the tube? (Surface tension = 0.072 N/m, density of water = 1000 kg/m³)
A.
0.5 m
B.
0.1 m
C.
0.2 m
D.
0.3 m
Solution
Using the formula h = 2γ/(ρgr), h = 2 × 0.072 N/m / (1000 kg/m³ × 9.81 m/s² × 0.0005 m) = 0.2 m.
Q. A liquid drop is formed on a surface. The angle formed between the tangent to the drop surface and the solid surface is called what?
A.
Contact angle
B.
Surface angle
C.
Tension angle
D.
Cohesion angle
Solution
The angle formed between the tangent to the drop surface and the solid surface is known as the contact angle, which indicates the wettability of the surface.
Q. If a capillary tube has a radius of 0.5 mm and the surface tension of the liquid is 0.072 N/m, what is the height of the liquid column in the tube? (Assume density = 1000 kg/m³)
A.
0.0144 m
B.
0.072 m
C.
0.0288 m
D.
0.036 m
Solution
Height = (2 × Surface Tension) / (Density × g × Radius) = (2 × 0.072 N/m) / (1000 kg/m³ × 9.81 m/s² × 0.0005 m) = 0.0144 m.
Understanding surface tension is crucial for students preparing for school and competitive exams. This concept not only appears frequently in various syllabi but also forms the basis for many practical applications in physics and chemistry. Practicing MCQs and objective questions on surface tension can significantly enhance your exam preparation, helping you to score better by reinforcing your understanding of important questions and concepts.
What You Will Practise Here
Definition and significance of surface tension in liquids
Key formulas related to surface tension and their applications
Factors affecting surface tension and their explanations
Practical examples illustrating surface tension in daily life
Diagrams and illustrations related to surface tension phenomena
Comparative analysis of surface tension in different liquids
Concept of capillarity and its relation to surface tension
Exam Relevance
Surface tension is a vital topic in the curriculum of CBSE, State Boards, NEET, and JEE. It often appears in the form of direct questions, numerical problems, and conceptual applications. Students can expect to encounter questions that require them to calculate surface tension, explain its effects, or analyze experimental setups. Familiarity with this topic can help students tackle both theoretical and practical questions effectively.
Common Mistakes Students Make
Confusing surface tension with viscosity, leading to incorrect answers in comparative questions.
Overlooking the units of measurement when solving numerical problems related to surface tension.
Misunderstanding the relationship between temperature and surface tension, which can affect calculations.
Failing to apply the concept of surface tension to real-life scenarios, which can hinder conceptual clarity.
FAQs
Question: What is surface tension? Answer: Surface tension is the property of a liquid's surface that allows it to resist an external force, due to the cohesive nature of its molecules.
Question: How does temperature affect surface tension? Answer: Generally, as temperature increases, surface tension decreases because the kinetic energy of the molecules increases, reducing cohesive forces.
Now is the time to boost your understanding of surface tension! Dive into our practice MCQs and test your knowledge to ensure you are well-prepared for your exams. Remember, consistent practice is key to mastering this important topic!
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