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    3.  A metal spoon is left in a bowl of hot soup.
                         After a few minutes,  the  handle becomes
                         hot even though  it  isn't  touching the soup.
                         Which statement  correctly  identifies  the
                         phenomenon?            (Pattern Recognition)

                                (a)   Heat is transferred through the
                                   spoon by the movement of fluid
                                   particles (convection).
                                                                              Which student is correct, and what principle
                                (b)   Heat  is  transferred through  the      of convection explains the smoke's direction?
                                   spoon  from the  hot  end to  the                                  (Abstract Thinking)
                                   cooler  handle by  conduction,  as
                                   the spoon is a solid.                            (a)   Farida, smoke moves downward
                                                                                       due to conduction, as heat travels
                                (c)   The handle becomes hot
                                   because it absorbs heat from the                    along the length of the stick.
                                   surrounding air through radiation.               (b)   Rohan, smoke rises upward due to
                                                                                       convection, because the hot smoke
                                (d)   Particles of the hot soup move into
                                   the spoon handle, causing it to                     is less dense than the surrounding
                                                                                       air and moves upward.
                                   become hot.
                                                                                    (c)   Both are partially right, smoke first
                      4.  In Ladakh, water is sprayed into freezing air
                         during winter to form ice stupas which melt                   goes down then curves up.
                         slowly in spring. Why does this method ensure              (d)   No one is correct as smoke
                         a water supply later?    (Abstract Thinking)                  spreads equally in all directions

                                (a)   Stupa's  ice melts  quickly  due                 from a downward stick.
                                   to  conduction  of heat  from  the      6.  Two identical test tubes are filled with equal
                                   ground.                                    amounts of water. Both are heated from below

                                (b)    Conical shape of ice stupa             by a candle. In Fig. (a), the thermometer bulb
                                   reduces heat gain, so melting              is near the bottom of the water. In Fig. (b),
                                   slows despite radiation.                   the thermometer bulb is near the top of the
                                                                              water. After two minutes, both thermometers
                                (c)   Freezing and melting of ice occur       are read.
                                   due to convection in air.                                               Thermometer

                                                                              Thermometer                      Water
                                (d)  Stupa's ice stores water and melts
                                   slowly by absorbing heat from the
                                   surrounding.                                         Water

                      5.  A burning incense  stick  is  fixed so it  points
                         straight  downward  — the burning tip  is at
                         the  bottom.  Farida  predicts:  'Smoke  will
                         travel downward because  the  stick  points                              Burning
                         down.' Rohan predicts:  'Smoke  will rise                                candle
                         upward regardless of stick orientation.'  The                                         Fig. (b)
                         experiment is carried out.                                  Fig. (a)

                                                                                           Heat Transfer in Nature    75

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