Distinguish between the following. Physical change and Chemical change Exothermic reaction and Endothermic reaction
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0
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2701
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March 23, 2018
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Describe how crystals of copper sulphate are prepared
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0
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13264
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March 23, 2018
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A student took a solution of copper sulphate in a beaker and put a clean iron nail into it and left it for about an hour
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0
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7376
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March 23, 2018
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If you leave a piece of iron in the open for a few days, it acquires a film of brownish substance, called rust. Do you think rust is different from iron?
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0
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4263
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March 23, 2018
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Give an example of a chemical reaction for each of the following situations: A change in colour is observed. A gas is evolved. Sound is produced. Formation of precipitate. Change of state from liquid to gas. Change of state from gas to liquid
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0
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3502
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March 23, 2018
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Give two examples for each of the following cases: Physical changes which are reversible. Physical changes which are not reversible. Chemical changes
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0
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1235
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March 23, 2018
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When chemical reaction takes place, what changes accompany the formation of new substances?
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0
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1295
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March 23, 2018
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Give example of two substances that can undergo physical and chemical changes, depending upon the conditions
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0
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1081
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March 23, 2018
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Why does a magnesium ribbon burn with a dazzling white flame?
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0
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2565
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March 23, 2018
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What is rust? How is it formed?
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0
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5784
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March 23, 2018
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How can iron articles be prevented from rusting?
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0
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628
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March 23, 2018
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Explain why rusting of iron objects is faster in coastal areas than in deserts
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0
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1258
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March 23, 2018
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Explain how painting of an iron gate prevents it from rusting
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0
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1666
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March 23, 2018
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Explain why burning of wood and cutting it into small pieces are considered as two different types of changes
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0
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1802
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March 23, 2018
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How would you show that setting of curd is a chemical change?
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0
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978
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March 23, 2018
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When a candle burns, both physical and chemical changes take place
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0
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1324
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March 23, 2018
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When baking soda is mixed with lemon juice, bubbles are formed with the evolution of a gas
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0
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1557
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March 23, 2018
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Explain the following: Lime water turns milky on passing carbon dioxide gas into it. Bubbles are produced when acetic acid is added to a solution of sodium hydrogencarbonate
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0
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3711
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March 23, 2018
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Classify the changes involved in the following processes as physical or chemical changes: Photosynthesis Dissolving sugar in water Burning of coal Melting of wax
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0
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594
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March 23, 2018
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