{"id":2984,"date":"2021-02-23T16:30:30","date_gmt":"2021-02-23T11:00:30","guid":{"rendered":"https:\/\/wordpress-505192-1602719.cloudwaysapps.com\/?p=2984"},"modified":"2021-02-23T17:32:32","modified_gmt":"2021-02-23T12:02:32","slug":"samacheer-kalvi-9th-science-solutions-chapter-7","status":"publish","type":"post","link":"https:\/\/samacheerguru.com\/samacheer-kalvi-9th-science-solutions-chapter-7\/","title":{"rendered":"Samacheer Kalvi 9th Science Solutions Chapter 7 Heat"},"content":{"rendered":"

You can Download\u00a0Samacheer Kalvi 9th Science Book Solutions<\/a>\u00a0Guide Pdf, Tamilnadu State Board help you to revise the complete Syllabus and score more marks in your examinations.<\/p>\n

Samacheer Kalvi 9th Science Solutions Chapter 7 Heat<\/h2>\n

Samacheer Kalvi 9th Science Heat Textbook Exercises<\/h3>\n

I. Choose the correct answer:<\/span><\/p>\n

Chapter 7 Heat Question 1.<\/strong>
\nCalorie is the unit of
\n(a) heat
\n(b) work
\n(c) temperature
\n(d) food
\nAnswer:
\n(a) heat<\/p>\n

Heat Lesson For 9th Class Question 2.<\/strong>
\nSI unit of temperature is
\n(a) fahrenheit
\n(b) joule
\n(c) Celsius
\n(d) kelvin
\nAnswer:
\n(d) kelvin<\/p>\n

9th Class Physics Heat Lesson Question 3.<\/strong>
\nTwo cylindrical rods of same length have the area of cross-section in the ratio 2:1. If both the rods are made up of same material, which of them conduct heat faster?
\n(a) Both rods
\n(b) Rod-2
\n(c) Rod-1
\n(d) None of them
\nAnswer:
\n(c) Rod-1<\/p>\n

Heat Lesson In Physics For Class 9 Question 4.<\/strong>
\nIn which mode of transfer of heat, molecules pass on heat energy to neighbouring molecules without actually moving from their positions?
\n(a) Radiation
\n(b) Conduction
\n(c) Convection
\n(d) Both B and C
\nAnswer:
\n(b) Conduction<\/p>\n

Lesson 7 Science Class 9 Question 5.<\/strong>
\nA device in which the loss of heat due to conduction, convection and radiation is minimized is
\n(a) Solar cell
\n(b) Solar cooker
\n(c) Thermometer
\n(d) Thermos flask
\nAnswer:<\/p>\n

    \n
  1. \u00a0(a) Heat<\/li>\n
  2. \u00a0(d) kelvin<\/li>\n
  3. \u00a0(c) Rod-1<\/li>\n
  4. \u00a0(b) Conduction<\/li>\n
  5. \u00a0(d) Thermos flask<\/li>\n<\/ol>\n

    II. Fill in the blanks.<\/span><\/p>\n

      \n
    1. The fastest mode of heat transfer is ……………….<\/li>\n
    2. During day time, air blows from ………… to …………….<\/li>\n
    3. Liquids and gases are generally …………….. conductors of heat.<\/li>\n
    4. The fixed temperature at which matter changes state from solid to liquid is called ………………<\/li>\n<\/ol>\n

      Answer:<\/p>\n

        \n
      1. radiation<\/li>\n
      2. land, sea<\/li>\n
      3. bad<\/li>\n
      4. melting point<\/li>\n<\/ol>\n

        III. Assertion and Reason type questions.<\/span><\/p>\n

        Mark the correct choice as:
        \n(a) If both assertion and reason are true and reason is the correct explanation of assertion.
        \n(b) If both assertion and reason are true but reason is not the correct explanation of assertion.
        \n(c) If assertion is true but reason is false.
        \n(d) If assertion is false but reason is true.<\/p>\n

        Samacheer Kalvi 9th Science Question 1.<\/strong>
        \nAssertion(A): Food can be cooked faster in copper bottom vessels.
        \nReason (R): Copper is the best conductor of heat.
        \nAnswer:
        \n(a) If both assertion and reason are true and reason is the correct explanation of assertion.<\/p>\n

        Samacheer Kalvi 9th Science Practical Question 2.<\/strong>
        \nAssertion(A): Maximum sunlight reaches earth\u2019s surface during the afternoon time.
        \nReason(R): Heat from the sun reaches earth\u2019s surface by radiation.
        \nAnswer:
        \n(b) If both assertion and reason are true but reason is not the correct explanation of assertion.<\/p>\n

        Class 9 Science Chapter 7 Question Answer Question 3.<\/strong>
        \nAssertion(A): When water is heated up to 100\u00b0C, there is no raise in temperature until all water gets converted <\/span>into water vapour.<\/span><\/p>\n

        Reason(R): Boiling point of water is 10\u00b0C.
        \n<\/span>Answer:
        \n<\/span>(c) If assertion is true but reason is false.<\/span><\/p>\n

        IV. Answer briefly.<\/span><\/p>\n

        Class 9th Science Solution Question 1.<\/strong>
        \nDefine conduction.
        \nAnswer:
        \nThe process of transfer of heat in solids from a region of higher temperature to a region of lower temperature without the actual movement of molecules is called conduction.<\/p>\n

        9th Science Samacheer Kalvi Question 2.<\/strong>
        \nIce is kept in a double-walled container. Why?
        \nAnswer:
        \nIce is kept in a double-walled container so as to prevent melting of ice from the heat absorbed present in the immediate surroundings. The vacuum present in between the two walls prevents the transfer of heat from the first to the second wall and hence the ice remains in the solid form for a longer time period.<\/p>\n

        9th Standard Question 3.<\/strong>
        \nHow does the water kept in an earthen pot remain cool?
        \nAnswer:
        \nAn earthen pot consists of small pores from which the water inside the pot constantly seeps out and gets evaporated due to the presence of high temperature around it. The evaporation process requires heat which is acquired from the surface of the pot, hence making the water and the pot cooler.<\/p>\n

        Question 4.
        \nDifferentiate convection and radiation.
        \nAnswer:<\/p>\n\n\n\n\n\n\n
        S.No.<\/td>\nConvection<\/td>\nRadiation<\/td>\n<\/tr>\n
        1.<\/td>\nFlow of heat through a fluid from places of higher temperature to places of lower temperature by movement of the fluid itself.<\/td>\nFlow of heat from one place to another by means of electromagnetic waves.<\/td>\n<\/tr>\n
        2.<\/td>\nConvection needs matter to be present.<\/td>\nRadiation can occur even in vacuum.<\/td>\n<\/tr>\n
        3.<\/td>\nConvection seen in daily life:<\/p>\n

        Hot air balloons, breeze, wind, chimney.<\/td>\n

        		Radiation in daily life:<\/p>\n

        White or light coloured cloths, highly polished surface of airplane, helps to reflect most of the heat radiation from the sun.<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n

        Question 5.
        \nWhy do people prefer wearing white clothes during summer?
        \nAnswer:
        \nPeople prefer white or light coloured clothes during summer as they are good reflectors of heat and hence, they keep us cool.<\/p>\n

        Question 6.
        \nWhat is specific heat capacity?
        \nAnswer:<\/p>\n

          \n
        • The specific heat capacity of a substance is defined as the amount of heat required to raise the temperature of 1 kg of the substance by 1\u00b0C or 1 K.<\/li>\n
        • Q = mC\u2206T, where Q is the quantity of heat required to raise the temperature and m is the mass of the body and AT is the change in temperature of the body.<\/li>\n
        • The SI unit of specific heat capacity is Jkg– 1<\/sup> K– 1<\/sup>. The most commonly used units of specific heat capacity are J\/kg\u00b0C and J\/g\u00b0C.<\/li>\n<\/ul>\n

          Question 7.
          \nDefine thermal capacity.
          \nAnswer:<\/p>\n

            \n
          • Heat capacity or thermal capacity is defined as the amount of heat energy required to raise the temperature of a body by 1\u00b0C. It is denoted by \u2018C\u2019.<\/li>\n
          • C = Q\/t, where C\u2019 is the heat capacity, \u2018Q\u2019 is the quantity of heat required and \u2018f\u2019 is rise in temperature.<\/li>\n
          • SI unit of heat capacity is J\/K. It is also expressed in cal\/\u00b0C, kcal\/\u00b0C or J\/\u00b0C.<\/li>\n<\/ul>\n

            Question 8.
            \nDefine specific latent heat capacity.
            \nAnswer:<\/p>\n

              \n
            • Specific latent heat is the amount of heat energy absorbed or liberated by unit mass of a substance during change of state without causing any change in temperature.<\/li>\n
            • Specific latent heat is given as L = Q\/m, where \u2018Q\u2019 is the amount of heat energy absorbed or liberated and \u2018m\u2019 is mass of a substance during its change of phase at a constant temperature.<\/li>\n
            • The SI unit of specific latent heat is J\/kg.<\/li>\n<\/ul>\n

              V. Answer in detail.<\/span><\/p>\n

              Question 1.
              \nExplain convection in daily life.
              \nConvection in daily life:
              \n(i) Hot air balloons: Air molecules at the bottom of the balloon get heated by a heat source and rise. As the warm air rises, cold air is pushed downward and it is also heated. When the hot air is trapped inside the balloon, it rises.
              \n\"Chapter
              \n(ii) Breeze: During day time, the air in contact with the land becomes hot and rises. Now the cool air over the surface of the sea replaces it. It is called sea breeze. During night time, air above the sea is warmer. As the warmer air over the surface of the sea rises, cooler air above the land moves towards the sea.
              \n\"Heat
              \n(iii) Winds: Air flows from area of high pressure to area of low pressure. The warm air molecules over hot surface rise and create low pressure. So, cooler air with high pressure flows towards low pressure area. This causes wind flow.
              \n(iv) Chimneys: Tall chimneys are kept in kitchen and industrial furnaces. As the hot gases and smoke are lighter, they rise up in the atmosphere.<\/p>\n

              Question 2.
              \nWhat are the changes of state in water? Explain.
              \nAnswer:
              \nAny matter around us can be in three forms: solid, liquid and gas, called as states of matter. Depending upon the temperature, pressure and transfer of heat, matter is converted from one state to another and is known as change of state in matter. There are different such processes in the change of state in matter.
              \n\"9th
              \nFor example;<\/p>\n

                \n
              • Water molecules are in liquid state at normal temperature. When water is heated to 100\u00b0C, it becomes steam or vapour which is a gaseous state of matter. The process by which a
                \nliquid is converted to vapour by absorbing heat is called boiling or vaporization.<\/li>\n
              • The temperature at which a liquid changes its state to gas is called boiling point.<\/li>\n
              • On reducing the temperature of the steam it becomes water again. The process by which a vapour is converted to liquid by releasing heat is called condensation. On reducing the temperature of water further to 0\u00b0C, it becomes ice which is a solid state of water.<\/li>\n
              • The process by which a liquid is converted to solid by releasing heat is called freezing. The
                \ntemperature by which a liquid changes its state to solid is called freezing point. Ice on
                \nheating, becomes water again by absorbing heat, a process known as melting.<\/li>\n
              • Dry ice changes directly to gaseous state without becoming liquid. This process is called
                \nsublimation.<\/li>\n<\/ul>\n

                Thus, water changes its state when there is a change in temperature.
                \n\"Heat<\/p>\n

                Question 3.
                \nHow can you experimentally prove that water is a bad conductor of heat? How is it possible to heat water easily while cooking.
                \nExperiment to prove that water is a bad conductor of heat:
                \nAnswer:
                \nTake a glass tube and drop an ice cube wrapped in wire gauze in it.
                \nNow fill 3\/4th of this tube with water and place it above the burner as shown in the figure.
                \nYou can observe that the water boils at the edge and the ice present in the bottom of the tube has not melted indicating that heat has not reached the bottom where the ice cube is present. This proves that water is a bad conductor of heat.
                \nIt is easy to heat water easily or quickly while cooking. This is because, while cooking the vessel or pan is usually covered with a lid.
                \n\"Lesson
                \nThis leads to three things;<\/p>\n

                  \n
                1. Radiation from the hot water is reflected back into the pan rather than being emitted<\/li>\n
                2. Free convection is effectively eliminated, and<\/li>\n
                3. Evaporative cooling’ is also eliminated.
                  \nThis in turn allows the water to be heated more easily.<\/li>\n<\/ol>\n

                  VI. Problems:<\/span><\/p>\n

                  Question 1.
                  \nWhat is the heat in joules required to raise the temperature of 25 grams of water from 0\u00b0C to 100\u00b0C? What is the heat in Calories? (Specific heat of water = 4.18 J\/g\u00b0C).
                  \nSolution:
                  \nGiven m = 25 g, \u2206T = (100 – 0) = 100\u00b0C
                  \nOr in terms of Kelvin (373.15 – 273.15) = 100K,
                  \nC = 4.18J\/g\u00b0C
                  \nHeat energy required, Q = m \u00d7 C \u00d7 \u2206T = 25 \u00d7 4.18 \u00d7 100 = 10450 J<\/p>\n

                  Question 2.
                  \nWhat could be the final temperature of a mixture of 100 g of water at 90\u00b0C and 600g of water at 20\u00b0C.
                  \nSolution:
                  \nTo find final temperature: \u2206Q = mc
                  \nlOOg of water originally at 90\u00b0C will loose an amount of heat,
                  \n\u2206Q = mc \u2206T
                  \n\u2206Q = 100 \u00d7 c \u00d7 (90 – T)
                  \nThe same amount of heat will be absorbed by 600g of water originally at 20\u00b0C to raise its temperature to T.
                  \n\u2206Q = 600 \u00d7 c \u00d7 (T – 30)
                  \n600C (T – 20\u00b0) = 100C (90\u00b0 – T)
                  \n6T – 120\u00b0 = 90\u00b0 – T
                  \n6T + T = 120\u00b0 + 90\u00b0
                  \n7T = 210\u00b0 \u21d2 T = 210\/7
                  \nT = 30\u00b0C<\/p>\n

                  Question 3.
                  \nHow much heat energy is required to change 2 kg of ice at 0\u00b0C into water at 20\u00b0C? (Specific latent heat of fusion of water = 3,34,000J\/kg, Specific heat capacity of water = 4200Jkg– 1<\/sup> K– 1<\/sup> ).
                  \nSolution:
                  \nTotal heat = Heat required to convert 2Kg of ice into water at 0\u00b0C + Heat required to convert 2Kg of water at 0\u00b0C to 2Kg of water at 20\u00b0C
                  \nHeat = m (hfw) + mc\u2206T
                  \nHere, m(mass of ice) = 2Kg
                  \nhfw (specific latent heat of water) = 3,34,000J\/Kg
                  \nC (specific heat capacity of water) = 4200JKg– 1<\/sup>K– 1<\/sup>
                  \nAT (Temperature difference) = 20\u00b0C
                  \nTherefore, Heat required = (2 \u00d7 334000) + (2 \u00d7 4200) (20 – 0)
                  \n= 668000 + 8400 (20)
                  \n= 668000+ 168000
                  \nHeat required = 8,36,000 J<\/p>\n

                  Activity<\/span><\/p>\n

                  Question 1.
                  \nTake a glass of water and put some ice cubes into it. Observe it for some time. What happens? The ice cubes melt and disappear. Why did it happen?
                  \nSolution:
                  \nIt is because heat energy in the water is transferred to the ice.<\/p>\n

                  Question 2.
                  \nTake metal rods of copper, aluminium, brass and iron. Fix a match stick to one end of each rod using a little melted wax. When the temperature of the far ends reach the melting point of wax, the matches drop off. It is observed that the match stick on the copper rod would fall first, showing copper as the best conductor followed by aluminum, brass and then iron.
                  \nAnswer:
                  \nYou can do the activity by yourself.<\/p>\n

                  Question 3.
                  \nDrop a few crystals of potassium permanganate down to the bottom of a beaker containing water. When the beaker is heated just below the crystals, by a small flame, purple streaks of water rise upwards and fan outwards.
                  \nAnswer:
                  \nYou can do the activity by yourself.<\/p>\n

                  Question 4.
                  \nTake some crushed ice cubes in a beaker and note down the temperature using thermometer. It will be 0\u00b0C. Now heat the ice i n the beaker. You can observe that ice is melting to form water. Record the temperature at regular intervals and it will remain at 0\u00b0C until whole ice is converted to liquid. Now heat the beaker again and record the temperature. You can notice that the temperature will rise up to 100\u00b0C and it will be at 100\u00b0C even after continuous heating until the whole mass of water in the beaker is vaporized.
                  \nAnswer:
                  \nYou can do the activity by yourself.<\/p>\n

                  Samacheer Kalvi 9th Science Heat In Text Problems<\/h3>\n

                  Question 1.
                  \nConvert the following,<\/p>\n

                    \n
                  1. \u00a025 \u00b0C to Kelvin<\/li>\n
                  2. 200 K to \u00b0C<\/li>\n<\/ol>\n

                    Solution:<\/p>\n

                      \n
                    1. Tk<\/sub> = T\u00b0C<\/sub> + 273.15
                      \nTk<\/sub> = 25 + 273.15 = 298.15 K<\/li>\n
                    2. T\u00b0C<\/sub> = Tk<\/sub> – 273.15
                      \nT\u00b0C<\/sub> = 200 – 273.15 = – 73.15 \u00b0C<\/li>\n<\/ol>\n

                      Question 2.
                      \nConvert the following.<\/p>\n

                        \n
                      1. 35\u00b0 C to Fahrenheit (\u00b0F)<\/li>\n
                      2. 14 \u00b0F to \u00b0C<\/li>\n<\/ol>\n

                        Solution:<\/p>\n

                          \n
                        1. T\u00b0F<\/sub> = T\u00b0C<\/sub> \u00d7 1.8 + 32
                          \nT\u00b0F<\/sub> = 25\u00b0 C \u00d7 1.8 + 32 = 77 \u00b0F<\/li>\n
                        2. T\u00b0C<\/sub> = (T\u00b0F<\/sub> – 32)\/1.8
                          \nT\u00b0C<\/sub> = (14\u00b0F<\/sub> – 32)\/1.8 = – 10 \u00b0C<\/li>\n<\/ol>\n

                          Question 3.
                          \nCalculate the heat energy required to raise the temperature of 2 kg of water from 10\u00b0C to 50\u00b0C. Specific heat capacity of water is 4200 JKg– 1<\/sup> K– 1<\/sup>.
                          \nSolution:
                          \nGiven m = 2 Kg, \u2206T = (50 – 10) = 40\u00b0C
                          \nIn terms of Kelvin, \u2206T = (323.15 – 283.15) = 40K,
                          \nC = 4200 J Kg– 1<\/sup> K,sup>- 1
                          \n\u2234 Heat energy required, Q = m \u00d7 C \u00d7 \u2206T = 2 \u00d7 4200 \u00d7 40 = 3,36,000 J<\/p>\n

                          Question 4.
                          \nAn iron ball requires 5000 J heat energy to raise its temperature by 20\u00b0C. Calculate the heat capacity of the iron ball.
                          \nSolution:
                          \nGiven, Q = 5000 J, \u2206T = 20\u00b0C or 20 K
                          \nHeat Capacity = \\(\\frac{\\text { Heat energy required, } \\mathrm{Q}}{\\text { Rise in temperature, } \\Delta \\mathrm{T}}=\\frac{5000}{20}\\) = 250 JK– 1<\/sup><\/p>\n

                          Question 5.
                          \nHow much heat energy is required to melt 5 kg of ice? (Specific latent heat of ice = 336 Jg– 1<\/sup>)
                          \nSolution:
                          \nGiven, m = 5 Kg = 5000g, L = 336 Jg– 1<\/sup>
                          \nHeat energy required = m \u00d7 L
                          \n= 5000 \u00d7 336
                          \n= 1680000J or 1.68 \u00d7 106<\/sup>J<\/p>\n

                          Question 6.
                          \nHow much boiling water at 100\u00b0C is needed to melt 2 kg of ice so that the mixture which is all water is at 0\u00b0C?
                          \n[Specific heat capacity of water = 4.2 JKg– 1<\/sup> and specific latent heat of ice = 336 Jg– 1<\/sup>].
                          \nSolution:
                          \nGiven, mass of ice = 2 kg = 2000 g.
                          \nLet m be the mass of boiling water required.
                          \nHeat lost = Heat gained.
                          \nm \u00d7 c \u00d7 \u2206t = m \u00d7 L
                          \nm \u00d7 4.2 \u00d7 (100 – 0) = 2000 \u00d7 336
                          \nm = \\(\\frac{2000 \\times 336}{4.2 \\times 100}\\)
                          \n= 1600 g or 1.6 kg.<\/p>\n

                          Samacheer Kalvi 9th Science Heat Additional Questions<\/h3>\n

                          I. Short answers questions.<\/span><\/p>\n

                          Question 1.
                          \nDefine radiation.
                          \nAnswer:
                          \nRadiation is a method of heat transfer that does not require particles to carry the heat energy.<\/p>\n

                          Question 2.
                          \nWhat is heat energy?
                          \nAnswer:
                          \nThe sum of the kinetic and potential energy is called the internal heat energy of the molecules. This internal energy when flows out is called heat energy.<\/p>\n

                          Question 3.
                          \nWhat are the three scales of temperature?
                          \nAnswer:
                          \nThere are three scales of temperature.<\/p>\n

                            \n
                          1. Fahrenheit scale<\/li>\n
                          2. Celsius or Centigrade scale<\/li>\n
                          3. Kelvin or Absolute scale.<\/li>\n<\/ol>\n

                            Question 4.
                            \nWhat is absolute zero?
                            \nAnswer:
                            \nThe temperature at which the pressure and volume of a gas theoretically reaches zero is called absolute zero.<\/p>\n

                            Question 5.
                            \nWhat is the concept of temperature?
                            \nAnswer:
                            \nTemperature is the degree of hotness or coolness of a body. The hotter the body is higher is its temperature.<\/p>\n

                            Question 6.
                            \nDifferentiate between the three temperature scales.
                            \nAnswer:<\/p>\n\n\n\n\n\n\n\n
                            Fahrenheit Scale<\/td>\nCelcius Scale<\/td>\nKelvin Scale<\/td>\n<\/tr>\n
                            32\u00b0F and 212\u00b0F are the freezing and boiling points respectively.<\/td>\n0\u00b0C and 100\u00b0C are the freezing and boiling points respectively.<\/td>\nOK represents absolute zreo. 373.15k and 273.15k are boiling and freezing points respectively.<\/td>\n<\/tr>\n
                            The interval has been divided into 180 parts.<\/td>\nThe interval has been divided into 100 parts.<\/td>\nA one degree difference in kelvin is equal to one degree difference in celcius.<\/td>\n<\/tr>\n
                            The formula for converting a Fahrenheit scale to Celcius scale is – C = 5\/9(F-32)<\/td>\nThe formula for converting a Celcius scale to Fahrenheit scale is<\/p>\n

                            – F = 9\/5C + 32<\/td>\n

                            		The formula for converting a Kelvin scale to Celcius scale is<\/p>\n

                            -C = K-273.15<\/td>\n<\/tr>\n

                            <\/td>\nAlso known as centigrade scale.<\/td>\nAlso known as absolute scale.<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n

                            II. Long answers questions.<\/span><\/p>\n

                            Question 1.
                            \nWrite specific heat capacity of any five substances.
                            \nAnswer:
                            \nSpecific heat capacity of a substance is defined as the amount of heat required to raise the temperature of 1 kg of the substance by 1\u00b0C or 1 K. The SI unit of specific heat capacity is Jkg– 1<\/sup>K– 1<\/sup>.<\/p>\n

                            Specific Heat Capacity of some common substances<\/p>\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n
                            S. No.<\/td>\nSubstance<\/td>\nSpecific Heat Capacity in JKg-1<\/sup> KT1<\/sup><\/td>\n<\/tr>\n
                            1.<\/td>\nLead<\/td>\n130<\/td>\n<\/tr>\n
                            2.<\/td>\nMercury<\/td>\n139<\/td>\n<\/tr>\n
                            3.<\/td>\nBrass<\/td>\n380<\/td>\n<\/tr>\n
                            4.<\/td>\nZinc<\/td>\n391<\/td>\n<\/tr>\n
                            5.<\/td>\nCopper<\/td>\n399<\/td>\n<\/tr>\n
                            6.<\/td>\nIron<\/td>\n483<\/td>\n<\/tr>\n
                            7.<\/td>\nGlass (flint)<\/td>\n504<\/td>\n<\/tr>\n
                            8.<\/td>\nAluminium<\/td>\n882<\/td>\n<\/tr>\n
                            9.<\/td>\nKerosene<\/td>\n2100<\/td>\n<\/tr>\n
                            10.<\/td>\nIce<\/td>\n2100<\/td>\n<\/tr>\n
                            11.<\/td>\nSea Water<\/td>\n3900<\/td>\n<\/tr>\n
                            12.<\/td>\nWater<\/td>\n4180<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n

                            Question 2.
                            \nDifferentiate between Conduction, Convection and Radiation.
                            \nAnswer:<\/p>\n\n\n\n\n\n\n\n\n
                            Conduction<\/td>\nConvection<\/td>\nRadiation<\/td>\n<\/tr>\n
                            Conduction takes place in solids<\/td>\nConvection takes place in liquids and gases.<\/td>\nAll hot objects give away heat by radiation.<\/td>\n<\/tr>\n
                            Heat transfer takes place on contact between hot to cold molecule.<\/td>\nThe hot molecules goes away from the heat source to the coldest region to the top.<\/td>\nHeat is carried as small packets of energy, which travel in straight line.<\/td>\n<\/tr>\n
                            Conduction does not occur in vacuum.<\/td>\nConvection does not occur in vacuum.<\/td>\nRadiation can occur in vacuum.<\/td>\n<\/tr>\n
                            Heat transfer can occur in any direction from hot to cold body.<\/td>\nHeat transfer occurs along the path of convection current from heat source to the coldest region on the top.<\/td>\nHeat transfer occurs when photons are met with an obstacle.<\/td>\n<\/tr>\n
                            Conduction is a relatively slow process.<\/td>\nThis process is faster than conduciton, but slower than radiation<\/td>\nRadiation is fastest way of heat transfer.<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n

                            Question 3.
                            \nWhat is latent heat of vapourisation. Explain with diagram.
                            \nAnswer:
                            \n\"Class
                            \nHeat energy is absorbed by a solid during melting and an equal amount of heat energy is liberated by the liquid during freezing, without any temperature change. It is called latent heat of fusion. In the same manner, heat energy is absorbed by a liquid during vaporization and an equal amount of heat energy is liberated by the vapor during condensation, without any temperature changes. This is called latent heat of vaporization.<\/p>\n

                            Question 4.
                            \nGive reasons why –<\/p>\n

                              \n
                            1. a steam burn is more damaging than a burn caused from boiling water at the same temperature.<\/li>\n
                            2. an igloo is built as a winter shelter<\/li>\n
                            3. gaps are left between railway tracks<\/li>\n
                            4. chimneys are located high up in kitchens and factories<\/li>\n
                            5. we wear woollen clothes in winter.<\/li>\n<\/ol>\n

                              Answer:<\/p>\n

                                \n
                              1. A steam bum is more damaging as when steam hits our skin it condenses to water and attains the temperature of our skin. There will be an energy release due to latent heat and fall in temperature. Whereas when boiling water fall on our skin, there is no transition in energy, only fall in temperature and heat transferred to the skin will be due to cooling.<\/li>\n
                              2. igloo is built as a winter shelter due to snow\u2019s insulating property. The inside of an igloo acts as an insulator and keeps it relatively warm.<\/li>\n
                              3. During summer, heat causes expansion in tracks that are made of metal. If gaps a re not left between tracks, the track may bend due to expansion and accidents can occur.<\/li>\n
                              4. As hot gases and smoke are lighter, they rise up. Therefore chimneys are placed high up in kitchens and factories, so that the hot air can rise up and go out into the atmosphere.<\/li>\n
                              5. We wear woollen clothes in winter, as wool acts as an insulator. The air trapped between the woollen sweater and our clothes acts as an insulator and does not allow air from outside to enter, thereby keeping us warm.<\/li>\n<\/ol>\n","protected":false},"excerpt":{"rendered":"

                                You can Download\u00a0Samacheer Kalvi 9th Science Book Solutions\u00a0Guide Pdf, Tamilnadu State Board help you to revise the complete Syllabus and score more marks in your examinations. Samacheer Kalvi 9th Science Solutions Chapter 7 Heat Samacheer Kalvi 9th Science Heat Textbook Exercises I. Choose the correct answer: Chapter 7 Heat Question 1. Calorie is the unit […]<\/p>\n","protected":false},"author":3,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"spay_email":"","footnotes":""},"categories":[3],"tags":[],"blocksy_meta":"","jetpack_featured_media_url":"","_links":{"self":[{"href":"https:\/\/samacheerguru.com\/wp-json\/wp\/v2\/posts\/2984"}],"collection":[{"href":"https:\/\/samacheerguru.com\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/samacheerguru.com\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/samacheerguru.com\/wp-json\/wp\/v2\/users\/3"}],"replies":[{"embeddable":true,"href":"https:\/\/samacheerguru.com\/wp-json\/wp\/v2\/comments?post=2984"}],"version-history":[{"count":0,"href":"https:\/\/samacheerguru.com\/wp-json\/wp\/v2\/posts\/2984\/revisions"}],"wp:attachment":[{"href":"https:\/\/samacheerguru.com\/wp-json\/wp\/v2\/media?parent=2984"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/samacheerguru.com\/wp-json\/wp\/v2\/categories?post=2984"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/samacheerguru.com\/wp-json\/wp\/v2\/tags?post=2984"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}