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Distinguish between the following. Physical change and Chemical change Exothermic reaction and Endothermic reaction
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0
|
2725
|
March 23, 2018
|
|
Describe how crystals of copper sulphate are prepared
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0
|
13295
|
March 23, 2018
|
|
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
|
7409
|
March 23, 2018
|
|
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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4315
|
March 23, 2018
|
|
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
|
3595
|
March 23, 2018
|
|
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
|
1255
|
March 23, 2018
|
|
When chemical reaction takes place, what changes accompany the formation of new substances?
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0
|
1304
|
March 23, 2018
|
|
Give example of two substances that can undergo physical and chemical changes, depending upon the conditions
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0
|
1114
|
March 23, 2018
|
|
Why does a magnesium ribbon burn with a dazzling white flame?
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0
|
2583
|
March 23, 2018
|
|
What is rust? How is it formed?
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|
0
|
5924
|
March 23, 2018
|
|
How can iron articles be prevented from rusting?
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|
0
|
637
|
March 23, 2018
|
|
Explain why rusting of iron objects is faster in coastal areas than in deserts
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|
0
|
1301
|
March 23, 2018
|
|
Explain how painting of an iron gate prevents it from rusting
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|
0
|
1686
|
March 23, 2018
|
|
Explain why burning of wood and cutting it into small pieces are considered as two different types of changes
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|
0
|
1825
|
March 23, 2018
|
|
How would you show that setting of curd is a chemical change?
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|
0
|
1004
|
March 23, 2018
|
|
When a candle burns, both physical and chemical changes take place
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|
0
|
1345
|
March 23, 2018
|
|
When baking soda is mixed with lemon juice, bubbles are formed with the evolution of a gas
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0
|
1593
|
March 23, 2018
|
|
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
|
3730
|
March 23, 2018
|
|
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
|
612
|
March 23, 2018
|
|
Classify the following processes into physical or chemical changes: Beating of aluminium metal to make aluminium foil. Digestion of food. Cutting of a log of wood into pieces. Burning of crackers
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0
|
3532
|
March 23, 2018
|