Class 11 Physics — Chapter 11: Thermal Properties of Matter Online Test

1. A blackbody emits maximum radiation at wavelength . Calculate the temperature of the blackbody.

2. How do detergents remove oil and grease stains from clothes?

3. A soil pore of radius retains water with surface tension . Calculate height of capillary rise ().

4. A cavitation bubble of radius in water has surface tension . Find excess pressure inside.

5. A soap bubble of radius has surface tension . Find the excess pressure inside it.

6. If the angle of contact , what will be the value of ?

7. A cubic centimeter of water splits into spherical droplets. If surface tension of water is , estimate the increase in surface energy. (Take density = ).

8. Which of the following is NOT an example of capillary action?

9. Which of the following is the correct statement of Bernoulli’s principle?

10. What does a Reynolds number greater than 3000 usually indicate?

11. For water at (), flowing at in a pipe of diameter , calculate .

12. A submarine moves at in seawater (). If its length is , calculate Reynolds number.

13. Water of density flows with velocity in a pipe of diameter . If viscosity is , calculate the Reynolds number.

14. Oil of density and viscosity flows through a pipe of diameter at velocity . Calculate Reynolds number.

15. A water droplet of radius falls through air. If viscosity of air is and density of water is , while air density is , find its terminal velocity.

16. A pollen grain of radius has density . If it falls in air (), calculate its terminal velocity. ()

17. In sedimentation analysis, particle size can be determined by measuring:

18. A dust particle of radius and density settles in air of viscosity . Find its terminal velocity. ()

19. If the atmospheric pressure is of Hg, the corresponding pressure in Pascal is approximately:

20. What happens to atmospheric pressure as altitude increases?

1. The viscosity of a gas at absolute temperature is approximately proportional to:

2. The pressure at the bottom of a liquid column is given by:

3. Stokes’ law gives the expression for:

4. If a force of 200 N is applied uniformly on a surface of area 0.5 m, the pressure is:

5. What type of meniscus is formed when angle of contact is acute ()?

6. Which statement best summarizes surface tension measurement techniques?

7. A solid cube of ice melts completely when heat is supplied. If latent heat of fusion is , find the mass of ice.

8. In free fall through air, a feather reaches terminal velocity much sooner than a stone because:

9. A wooden block of density floats in water. If the height of the block is 30 cm, what is the depth submerged?

10. In real-world flows, why does the simple form of Bernoulli’s equation need modification?

11. Which statement best summarizes the relationship between surface energy and surface tension?

12. Which of the following conditions ensures that terminal velocity exists for a falling body in a fluid?

13. In a Venturimeter, the discharge rate of fluid is proportional to:

14. A small steel ball is dropped in a jar of oil. Which of the following statements is true?

15. In Bernoulli’s derivation, kinetic energy per unit volume of a fluid is:

16. Why is Bernoulli’s principle limited in medical applications like blood flow analysis?

17. Why are gaps left between concrete slabs on roads and pavements?

18. Why do gases fill the entire container, unlike liquids?

19. Which assumption is NOT valid in Bernoulli’s principle?

20. Which statement best summarizes the importance of angle of contact?

21. Which of the following liquids exhibits an obtuse angle of contact with glass?

22. The emissive power of a blackbody at is:

23. In medicine, why must ultrasound contrast bubbles be smaller than red blood cells?

24. A 2 kg block of ice at is converted into water at . If specific heat of ice = 2100 J/kgK, latent heat of fusion = , specific heat of water = 4200 J/kgK, find total heat absorbed.

25. Which viscometer uses the principle of rotational resistance in fluid?

26. Why does oil spread easily on water surface?

27. Why does a soap film have surface energy equal to ?

28. Which of the following explains why toothpaste comes out uniformly when the tube is pressed?

29. At what height will the atmospheric pressure reduce to half of its value at the surface, assuming air temperature is constant at ? (Take molar mass of air , , ).

30. Why is capillary action important for plant physiology?

1. A mountain climber finds that the barometric pressure has dropped to of Hg from the normal . Estimate the altitude gained. (Density of Hg = ).

2. At what depth in water (density ) will the pressure increase by ?

3. What is the lowest possible temperature called?

4. For a liquid with contact angle , surface tension , density , and tube radius , capillary rise is proportional to:

5. In free fall through air, a feather reaches terminal velocity much sooner than a stone because:

6. The advantage of hydraulic systems over mechanical systems is:

7. What is the main role of detergents in cleaning?

8. Which of the following liquids exhibits an obtuse angle of contact with glass?

9. Which factor does NOT affect the stability of a soap bubble?

10. Why can some insects like water striders walk on water?

11. Which of the following is the correct statement of Bernoulli’s principle?

12. A small steel ball is dropped in a jar of oil. Which of the following statements is true?

13. A liquid film of area has surface tension . Find its surface energy if it has two free surfaces.

14. A human body radiates at body temperature . If body surface area is , calculate emissivity. ()

15. In engineering, why is it essential to know the thermal expansion properties of materials?

16. If Reynolds number in a chemical reactor is very high, what does it signify?

17. In a pipe, the flow changes from laminar to turbulent when:

18. A fluid of viscosity , density , flows at velocity through a pipe of diameter . Find Reynolds number.

19. In streamline flow, the velocity of fluid:

20. The dimension of coefficient of viscosity is:

21. A submarine moves at in seawater (). If its length is , calculate Reynolds number.

22. Which liquid will show higher capillary rise in a glass tube of equal radius?

23. Why are gaps left between concrete slabs on roads and pavements?

24. In surface chemistry, adsorption of gases on solids is influenced by:

25. Which assumption is NOT valid in Bernoulli’s principle?

26. What does a Reynolds number greater than 3000 usually indicate in pipe flow?

27. Which law gives the relationship between viscous force and velocity gradient in a liquid?

28. Bernoulli’s equation is derived from which fundamental law of physics?

29. A soap solution has surface tension . Calculate the work done in blowing a bubble of radius .

30. What happens to the acceleration of a particle as it approaches terminal velocity?

31. What is the primary factor that governs the transition from laminar to turbulent flow in a fluid?

32. Why are bimetallic strips used in electric irons?

33. In the case of a falling sphere, terminal velocity will be reached more quickly if:

34. According to Stokes’ law, the viscous force on a small sphere moving with velocity through a fluid is:

35. A liquid rises to a height in a capillary tube. If angle of contact is , the expression becomes:

36. A pollen grain of radius has density . If it falls in air (), calculate its terminal velocity. ()

37. A jar contains two immiscible liquids: water () of height 3 m, and oil () of height 2 m above it. Find the pressure at the bottom of the jar.

38. Why does turbulence occur at high Reynolds numbers?

39. Which of the following is a branch of physics that deals with the study of heat and its effects on matter?

40. In soil, water spreads through small pores between particles primarily due to:

41. In Reynolds’ experiment, when the velocity of water is gradually increased, the dye streak starts oscillating and breaking up. This shows:

42. Which of the following best summarizes the significance of Reynolds number?

43. In turbulent flow through a pipe, head loss due to friction is proportional to:

44. Which of the following is a limitation of Stokes’ law?

45. Why does water spread easily on a clean glass surface?

46. The SI unit of coefficient of viscosity is:

47. In Jaeger’s bubble pressure method, the maximum pressure required to form a bubble of radius at the tip of a tube is given by:

48. The expression for critical velocity in terms of Reynolds number is:

49. Which of the following explains why detergent-treated water wets cloth more effectively?

50. If the radius of a capillary tube is , surface tension , density , contact angle , find capillary rise.