Science and Technology I · Textbook solutions

Heat

Every solved example, exercise, and miscellaneous question — in the order the textbook teaches them. · 22 questions

Exercise

22 q
  1. Fill in the blanks and rewrite the sentence.
    Ex Q1(a)
    The amount of water vapour in air is determined in terms of its …………
  2. Ex Q1(b)
    If objects of equal masses are given equal heat, their final temperature will be different. This is due to difference in their ……………...
  3. Ex Q1(c)
    During transformation of liquid phase to solid phase, the latent heat is …………..
  4. Ex Q2
    Observe the following graph. Considering the change in volume of water as its temperature is raised from 0 ∘C0\ ^\circ\text{C}, discuss the difference in the behaviour of water and other substances. What is this behaviour of water called?
  5. Ex Q3
    What is meant by specific heat capacity? How will you prove experimentally that different substances have different specific heat capacities?
  6. Ex Q4
    While deciding the unit for heat, which temperatures interval is chosen? Why?
  7. Ex Q5
    Explain the following temperature versus time graph.
  8. Explain the following:
    Ex Q6(a)
    What is the role of anomalous behaviour of water in preserving aquatic life in regions of cold climate?
  9. Ex Q6(b)
    How can you relate the formation of water droplets on the outer surface of a bottle taken out of refrigerator with formation of dew?
  10. Ex Q6(c)
    In cold regions in winter, the rocks crack due to anomalous expansion of water.
  11. Answer the following:
    Ex Q7(a)
    What is meant by latent heat? How will the state of matter transform if latent heat is given off?
  12. Ex Q7(b)
    Which principle is used to measure the specific heat capacity of a substance?
  13. Ex Q7(c)
    Explain the role of latent heat in the change of state of a substances?
  14. Ex Q7(d)
    On what basis and how will you determine whether air is saturated with vapour or not?
  15. Read the following paragraph and answer the questions. If heat is exchanged between a hot and cold object, the temperature of the cold object goes on increasing due to gain of energy and the temperature of the hot object goes on decreasing due to loss of energy. The change in temperature continues till the temperatures of both the objects attain the same value. In this process, the cold object gains heat energy and the hot object loses heat energy. If the system of both the objects is isolated from the environment by keeping it inside a heat resistant box (meaning that the energy exchange takes place between the two objects only), then no energy can flow from inside the box or come into the box.
    Ex Q8(i)
    Heat is transferred from where to where?
  16. Ex Q8(ii)
    Which principle do we learn about from this process?
  17. Ex Q8(iii)
    How will you state the principle briefly?
  18. Ex Q8(iv)
    Which property of the substance is measured using this principle?
  19. Solve the following problems:
    Ex Q9(a)
    Equal heat is given to two objects A and B of mass 1 g. Temperature of A increases by 3 ∘C3\ ^\circ\text{C} and B by 5 ∘C5\ ^\circ\text{C}. Which object has more specific heat? And by what factor?
  20. Ex Q9(b)
    Liquid ammonia is used in ice factory for making ice from water. If water at 20 ∘C20\ ^\circ\text{C} is to be converted into 2 kg ice at 0 ∘C0\ ^\circ\text{C}, how many grams of ammonia are to be evaporated? (Given: The latent heat of vaporization of ammonia = 341 cal/g)
  21. Ex Q9(c)
    A thermally insulated pot has 150 g ice at temperature 0 ∘C0\ ^\circ\text{C}. How much steam of 100 ∘C100\ ^\circ\text{C} has to be mixed to it, so that water of temperature 50 ∘C50\ ^\circ\text{C} will be obtained? (Given : latent heat of melting of ice = 80 cal/g, latent heat of vaporization of water = 540 cal/g, specific heat of water = 1 cal/g ∘C1\ \text{cal/g}\ ^\circ\text{C})
  22. Ex Q9(d)
    A calorimeter has mass 100 g and specific heat 0.1 kcal/kg ∘C0.1\ \text{kcal/kg}\ ^\circ\text{C}. It contains 250 gm of liquid at 30 ∘C30\ ^\circ\text{C} having specific heat of 0.4 kcal/kg ∘C0.4\ \text{kcal/kg}\ ^\circ\text{C}. If we drop a piece of ice of mass 10 g at 0 ∘C0\ ^\circ\text{C}, What will be the temperature of the mixture?