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Page 69 - CT&AI_CLasa_7_Part_1
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    After a few days, rust appears only in jar C.    10.  Choose the correct algorithm to test electrical
                         What is the correct conclusion?                      conductivity:         (Algorithmic Thinking)
                                                    (Decomposition)                 (a)   Observe   Touch   Conclude

                                (a)   Only air causes rusting.                      (b)  Connect battery   Insert material

                                (b)   Only water causes rusting.                          Check bulb glow

                                (c)   Both air and water are required               (c)   Heat material   Break it
                                   for rusting.                                        Observe

                                (d)   Rusting does not need air.                    (d)  Drop material   Listen to sound

                                       A student is given an unknown material and performs the following steps:
                                       •  Step 1: Checks if it is shiny.
                                       •  Step 2: Tests if it conducts electricity.
                                       •  Step 3: Hammers it to see if it flattens.
                                       •  Step 4: Drops it to check if it produces any sound.

                                       The student observes that the material is shiny, conducts electricity, flattens on
                                       hammering, and produces a ringing sound when dropped.
                                       Based on the observation, what can the student conclude about the material?
                                             (a)  It is a non-metal because it is shiny.

                                             (b)  It is a metal because it shows all the key metallic properties.

                                             (c)  The material flattens on hammering, so it must be a non-metal.

                                             (d)   The material cannot be classified as a metal or non-metal based only
                                                 on these observations.

                                                                                 The World of Metals and Non-metals   67

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