|
Distinguish between the following. Physical change and Chemical change Exothermic reaction and Endothermic reaction
|
|
1
|
1060
|
March 23, 2018
|
|
Describe how crystals of copper sulphate are prepared
|
|
1
|
11257
|
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
|
|
1
|
4905
|
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?
|
|
1
|
2030
|
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
|
|
1
|
1088
|
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
|
|
1
|
468
|
March 23, 2018
|
|
When chemical reaction takes place, what changes accompany the formation of new substances?
|
|
1
|
614
|
March 23, 2018
|
|
Give example of two substances that can undergo physical and chemical changes, depending upon the conditions
|
|
1
|
364
|
March 23, 2018
|
|
Why does a magnesium ribbon burn with a dazzling white flame?
|
|
1
|
1981
|
March 23, 2018
|
|
What is rust? How is it formed?
|
|
1
|
1942
|
March 23, 2018
|
|
How can iron articles be prevented from rusting?
|
|
1
|
290
|
March 23, 2018
|
|
Explain why rusting of iron objects is faster in coastal areas than in deserts
|
|
1
|
895
|
March 23, 2018
|
|
Explain how painting of an iron gate prevents it from rusting
|
|
1
|
1179
|
March 23, 2018
|
|
Explain why burning of wood and cutting it into small pieces are considered as two different types of changes
|
|
1
|
1254
|
March 23, 2018
|
|
How would you show that setting of curd is a chemical change?
|
|
1
|
565
|
March 23, 2018
|
|
When a candle burns, both physical and chemical changes take place
|
|
1
|
861
|
March 23, 2018
|
|
When baking soda is mixed with lemon juice, bubbles are formed with the evolution of a gas
|
|
1
|
1065
|
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
|
|
1
|
2459
|
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
|
|
1
|
353
|
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
|
|
1
|
1118
|
March 23, 2018
|
