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Page 71 - CT&AI_CLasa_7_Part_1
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    What should be filled in place of 'X'?               Which  observation  supports  the  idea  of
                                                (Pattern Recognition)         erosion?                   (Decomposition)
                                (a)  Only shape changes                             (a)   Breaking rocks

                                (b)  Only state changes                             (b)   Movement of sediments

                                (c)   New substance is formed                       (c)   Burning wood

                                (d)   No change occurs                              (d)  Melting ice

                      6.  Which pattern  do the following changes          9.  A student is given four observations:
                         follow?
                                                                              1.   A solid turns into  liquid  on heating  and
                         •  Rusting of iron                                     becomes solid again on cooling.
                         •  Burning of wood
                                                                              2.   A  substance  burns and  produces  heat,
                         •  Formation of curd  (Pattern Recognition)            light, and ash.
                                (a)   All these changes are reversible.       3.   A  white  liquid  turns  milky  when a  gas  is
                                                                                passed through it.
                                (b)   All these changes are physical
                                   changes.                                   4.   A metal object develops a reddish-brown
                                                                                coating over time.
                                (c)   All these changes form new
                                   substances.                                The student is asked to classify these changes
                                                                              on the basis of characteristics  such as
                                (d)   All these changes involve change        reversibility,  formation  of new substances,
                                   in shape only.                             and energy changes.
                      7.  Identify the correct pattern:                       Which pair represents only chemical changes?

                         Set A: Melting butter, boiling water, freezing                                  (Decomposition)
                         water
                                                                                    (a)   1 and 2       (b)    1 and 4
                         Set B: Burning paper, rusting iron, baking cake
                                                (Pattern Recognition)               (c)  2, 3 and 4     (d)   1, 3 and 4

                                (a)   Both sets include reversible changes.   10.  A process occurs as follows:

                                (b)   Set A contains reversible changes,        Step 1: Rocks break into smaller pieces.
                                   while set B contains irreversible          Step 2: These pieces are transported.
                                   changes.                                   Step 3: They settle in new locations.

                                (c)   Set A includes chemical changes,        Which option correctly identifies these three
                                   while set B includes physical              steps?                (Algorithmic Thinking)
                                   changes.
                                                                                    (a)   Combustion   weathering   erosion
                                (d)   Both sets contain irreversible
                                   changes.                                         (b)  Deposition   combustion   erosion

                      8.  Over  many  years, rocks break  into  smaller             (c)   Erosion   deposition   weathering
                         pieces  due  to  heat,  water, and plant  roots.
                         These pieces are then carried away by rivers               (d)  Weathering   erosion   deposition
                         and wind and are deposited in other places.

                                                                           Changes Around Us: Physical and Chemical   69

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