NEET UG - Applications of surface tension including drops, bubbles and capillary rise One Line Questions & Answers

1. If the surface tension of water is 0.07 N/m, and it rises 2 cm in a capillary tube of radius 0.5 mm, what is the approximate angle of contact? — 60 degrees

2. The excess pressure inside a soap bubble is given by the formula: — 4S/r

3. The excess pressure inside a liquid drop is given by the formula: — 2S/r

4. The excess pressure inside a liquid drop is less than that of a soap bubble of the same radius because: — A bubble has two free surfaces, while a drop has one

5. Capillary depression occurs when the angle of contact is: — Obtuse

6. What is the term for the force of attraction between molecules of the same substance? — Cohesion

7. Which of the following liquids exhibits the highest surface tension at room temperature? — Mercury

8. The phenomenon that allows a needle to float on the surface of water if placed carefully is: — Surface tension

9. The phenomenon of a water strider walking on water is an example of: — Surface tension

10. When a liquid does not wet the surface, the meniscus in a capillary tube is: — Convex

11. For a liquid that wets the surface, the meniscus in a capillary tube is: — Concave

12. The shape of a liquid surface in contact with the atmosphere where adhesive forces are stronger than cohesive forces is: — Concave

13. If the radius of a capillary tube is doubled, the rise of liquid in the capillary due to surface tension will be: — Halved

14. In a capillary tube, the pressure at the level of the liquid surface outside the tube is: — Greater than the pressure inside the liquid at the same level

15. The rise of water in the narrow pores of soil is primarily due to: — Capillary action

16. Surface tension of a liquid is defined as: — Force per unit length acting parallel to the surface

17. Which of the following is NOT an application of surface tension? — Buoyancy of a ship

18. If two soap bubbles of different radii are joined by a tube, air will flow: — From the smaller bubble to the larger bubble

19. Which force is dominant in holding a water droplet to a leaf? — Surface tension (adhesion)

20. The formation of spherical raindrops is a direct consequence of: — Surface tension minimizing surface area

21. What causes the formation of a liquid film in a soap bubble? — Surface tension of the soap solution

22. If the surface tension of a liquid is 'S' and the radius of a capillary tube is 'r', and the angle of contact is 'θ', the height of capillary rise 'h' is given by: — h = 2S cos(θ) / (ρgr)

23. A soap bubble has two free surfaces, while a liquid drop has only one. Therefore, the excess pressure inside a soap bubble is: — Half that of a liquid drop of the same radius

24. Which property explains why water forms beads on a waxed surface? — High cohesion, low adhesion

25. When a liquid surface is concave, the pressure in the liquid just below the surface is: — Higher than the pressure just above the surface

26. If the angle of contact is 90 degrees, the liquid level in the capillary tube will be: — At the same level as the surrounding liquid

27. Why does a hot liquid have lower surface tension than a cold liquid? — Decreased cohesive forces at higher temperatures

28. What happens to the surface tension of a liquid when its temperature is increased? — It decreases

29. Which of the following statements about surface tension is incorrect? — It is measured in units of force per unit area.

30. If a liquid has a high surface tension, it means: — Its molecules have strong cohesive forces

31. The pressure difference across a curved liquid surface is given by: — Laplace's pressure formula

32. Surface tension is a property of: — Liquids only

33. The unit of surface tension is: — Newton per meter (N/m)

34. In capillary rise, the liquid rises in a capillary tube if the angle of contact between the liquid and the tube wall is: — Acute (less than 90 degrees)

35. The force of surface tension acts: — Parallel to the surface and tangential to the surface

36. The phenomenon of capillary action is utilized in: — Lamps (wick action)

37. Which factor does NOT affect the height of capillary rise? — Volume of the liquid

38. In the context of capillary rise, 'ρ' represents: — Density of the liquid

39. The energy required to increase the surface area of a liquid by a unit amount is equal to: — Surface energy

40. The height 'h' of capillary rise is inversely proportional to: — Radius of the tube (r)

41. The term 'wetting' in surface tension refers to: — The tendency of a liquid to spread over a solid surface

42. The capillary rise method is used to determine: — The surface tension of the liquid

43. The excess pressure in a bubble is due to: — The surface tension of the liquid film

44. In the case of capillary rise, the upward force due to surface tension is balanced by: — The weight of the liquid column

45. A very fine hole in a boat can cause it to sink because: — The weight of the water entering increases the boat's weight

46. What is the role of detergents in washing clothes? — They decrease the surface tension of water, allowing it to penetrate fabrics better

47. Why do aeroplane wings often have a coating to repel water? — To decrease surface tension and improve aerodynamics

48. Why do painters prefer brushes with fine bristles? — To decrease surface tension of the paint for better spreading

49. Which phenomenon is responsible for the spherical shape of a liquid drop in the absence of gravity? — Surface tension

50. The ability of a liquid to rise or fall in a narrow tube due to surface tension and adhesion is called: — Capillarity

Applications of surface tension including drops, bubbles and capillary rise - One Line Questions