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Page 70 - CT&AI_CLasa_7_Part_1
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    Changes Around

                                                                              Us: Physical and
                                     5                                                Chemical

                                               computational thinking quest

                    Tick ( ) the correct option.
                      1.  Riya kept an iron nail in water for a few days.     Based  on  the observation,  which  of the
                         She observed that  a reddish-brown layer             following best explains  why the  flame of
                         formed on its surface.                               candle B gets extinguished?
                         Which of the following conclusions is correct?                               (Abstract Thinking)
                                                  (Abstract Thinking)               (a)   The wax is completely used up.
                                (a)   It is a physical change because
                                   only colour changes.                             (b)   The temperature of the candle
                                                                                       decreases.
                                (b)   It is a chemical change because a
                                   new substance is formed.                         (c)   The supply of oxygen is cut off.
                                (c)   It is a reversible change because             (d)   The flame is blown out by moving air.
                                   iron can be cleaned.
                                                                           4.  Observe the pattern:
                                (d)   It is a temporary change as it lasts
                                   for only a few days.                       •  Ripening of fruits   Desirable
                                                                              •  Cooking of food   Desirable
                      2.  Which group contains only chemical changes?
                                                  (Abstract Thinking)         •  Rusting of iron   Undesirable
                                                                              •  Food spoilage   Undesirable
                                (a)   Melting, boiling, freezing
                                                                              Which  of the  following matches  the
                                (b)   Rusting, burning, baking                undesirable pattern?  (Pattern Recognition)

                                (c)   Cutting, folding, stretching                  (a)   Germination of seeds

                                (d)   Dissolving, melting, freezing                 (b)   Drying of clothes
                      3.  Observe the following diagram carefully:
                                                                                    (c)   Pollution due to burning fuels

                                                                                    (d)  Making compost

                                                                           5.  Observe the pattern:
                                                                                   Change              Observation
                                                                                 Cutting apple        Shape changes
                                                                                 Boiling water        State changes
                                    A               B                            Burning coal               X

                     68        Computational Thinking-7 (Science)

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