File No.22/04/07/09/2014
VI CLASS - IIT/N.T.S.E FOUNDATION - OLYMPIAD
ANDHRA PRADESH - TELANGANA
2014-2015 PROGRAM M E
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4th- CHANGES AROUND US - SOLUTION
1.
If there is change in substance, the change is not reversible.
2.
Blooming of flower, growth of a tree and decaying of leaf are chemical changes.
3.
Glowing of an electric bulb involves change of colour, change of temperature and it is physical reversible
change.
4.
If there is change in shape/size (or) colour (or) temperature it is physical change.
5.
Change of substance taking place during tearing of paper.
6.
Change of Bud to flower is reversible change.
8.
Eruption of volconoes is a natural non-periodic change.
9.
Cell used in torch light undergoes chemical change.
10.
Cooking of food is an endothermic, an irroversible change, and it also changes the internal strcture of food.
11.
Food, when kept in refrigerator at low temperature undergoes slow chemical change.
12.
Photosynthesis by green plants is a chemical
2014change.
- 2015
13.
Stretching of a bow string to shoot an arrow is example of a physical and reversible change.
14.
A change is called a chemical change when it involves production of new substances.
15.
If two substances interact to produce a change they will do so only if the interaction is under the right
conditions.
16.
The lightening of a match stick is a fast chemical change is correct statement.
17.
Evaporation of petrol is a physical change is correct.
19.
Eruption of volconoes is an undesirable change.
20.
Melting of wax is a reversible change.
1.
A change in which a new substance is formed may be a chemical change, Nuclear reaction.
2.
The mass of the substance does not change when water freezes.
3.
A change in which there is no change in chemical properties is physical change.
CHALLENGER
1
CHEMISTRY - CHAPTER SOLUTIONS - 4
File No.22/04/07/09/2014
VI CLASS - IIT/N.T.S.E FOUNDATION - OLYMPIAD
4.
A physical change is reversible.
5.
Exploding a cracker is an irreversible change and chemical change.
6.
Solar energy is coverted to chemical energy during photosynthesis.
7.
Ploughing of a field is an irreversible change
8.
Breaking of a glass rod is a physical change and irrversible change.
9.
Melting of glass is a physical change and reversible change.
10.
Formation of seed from flowers is an irrversible change.
11.
Formation of cloud is reversible change and physical change.
12.
Making chapattis from flour is a chemical change.
13.
Earthquake is a fast change
14.
Cooking of food is a slow change.
15.
The burning of kerosene a revesible change
16.
A large surface area water to evaporate faster.
17.
In rusting light is absored.
18.
Milk to panner be reversed.
19.
Conversion of a solid to liquid by heating is called melting.
20.
Change of day and night a man-made change.
BRAIN TWISTERS
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1.
Germination of a mustard seed into a seedling is a slow change, Burning of a sparkle is an irreversible fast
change and Water changing to ice is a slow change are correct statement.
2.
Rusting of articles of iron, Flooding of rivers in rainy season and Earth Quakes are undesirable changes.
3.
Burning of cool is permanent change and Burning of candle wax is permanent change are true statements.
4.
Formation of new substance and Change in weight are occur during physical changes.
5.
Always new substances are produced during a chemical change and Permanent change and can’t be
reversed easily are true for a chemical change.
6.
a) Composition of the molecules of the substances is altered
-
Chemical change
b) Change takes place in colour and solubility of a substance only
-
Physical change
c) Energy required for completion of the change is released on reversing the change - Chemical change,
physical change.
d) Matter undergoes changes but the total mass is unaltered 7.
a) Water on heating to form
CHALLENGER
-
chemical change
Steam, Physical change
2
CHEMISTRY - CHAPTER SOLUTIONS - 4
File No.22/04/07/09/2014
8.
9.
10.
VI CLASS - IIT/N.T.S.E FOUNDATION - OLYMPIAD
b) 20 g of salt dissolved in water
change
-
20 g of salt left on evaporation, Physical
c) Zinc oxide
-
ZnO
d) Expansion or contraction of metals on heating
-
a) Desirable change
curd from milk
-
Beating of heart, Sneezing, Formation of
b) Undesirable change
-
Flooding of rivers in rainy season
c) Periodic change
-
Beating of heart
d) Non-periodic change
Flooding of rivers in rainy season
-
Sneezing, Formation of curd from milk,
a) On heating ZnO changes to
-
Yellow colour
b) On heating PbO changes to
-
Reddish brown colour
c) Above two changes are
-
Physical change
d) Curdling of milk
-
Chemical change
a) Melting of ice
-
Reversible change, Physical change
b) Germination of seeds
-
Chemical change
c) Lead monoxide
-
Changes in colour by heating
d) Heating and cooling of a platinum wire is
in colour by heating
11.
Reversible change, Physical change, Changes
Assertion and Reason are definations of physical and chemical changes.
Reason does not explains assertion.
12.
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Physical change
2014 - 2015
Burning of LPG is chemical change. LPG burns with a paleblue flame and diberates colourless CP2 gas
which can be converted back to LPG.
Reason explained assertion.
13.
Reason is False. But assertion is true.
14.
Phases fo moon is example for periodic change.
Earth quakes are example for non-periodic change.
Reason does not explained assertion.
15.
Assertion and Reason are defination of physical and chemical changes.
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Reason does not explains assertion.
16.
Melting of snow on the mountains in the summer is Desirable change.
17.
Food turning bad in summer is Undesirable change.
18.
Formation of nature from animal dung and dead leaves is Desirable change.
19.
Formation earth quake is Desirable change.
CHALLENGER
3
CHEMISTRY - CHAPTER SOLUTIONS - 4
File No.22/04/07/09/2014
VI CLASS - IIT/N.T.S.E FOUNDATION - OLYMPIAD
20.
The classification of changes around us based on direction of change are two types.
1.
Falling of leaves from a tree, The ageing of plants and Weathering of rocks are irreversible change.
2.
Assertion and Reason are defination of reversible change and permanent in nature.
Reason does not explains assertion.
3.
The heat produced by the burning of petrol in the engines of cars or scooters, To farmers, it is necessary
spraying of chemicals on vegetables and fruits to kill insects are desirable and Cutting of wood results in
imbalance in nature and The poisonous gases like carbon monoxide and nitric oxide are produced, when
fuels are burnt are undesirable.
4.
a) Sugar on strong heating
-
Carbon and steam
b) Strong heating of mercuric oxide
-
Mercury and oxygen
c) Burning of candle wax
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Carbon dioxide and steam
d) Burning of magnesium
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Magnesium oxide
5.
When mix we iron fillings with sulphur and grind it, a physical change takes place.
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If we heat the mixture a chemical change takes place.
7.
Evaporation of water by the heat of sun, Expansion and contraction of metals on heating and Crystallisation
of salts from their solutions are physical changes.
8.
That cannot be reversed baking of dough into bread is a kind of change.
9.
Salt can be separated from its solution (salt dissolved in water), because Mixing of salt in water is a change
that can be reversed by evaporation.
10.
Heartbeat is a periodic change
11.
Sublimation is a chemical change.
12.
In gerneral, on heating metals expand.
13.
Expands first, then no cooling contracts and fits into the wooden wheel.
14.
Bursting of crackers is considered as fact change.
15.
Bursting of cracker is a reversible change.
16.
If plaster of paris is added with water then the change is Chemical change.
17.
Folding of paper is an example for Reversible.
18.
Formation of petrol is a Fast change.
19.
Galvanisation is method to prevent rust.
20.
The solution turns from blue to green, A brown layer is deposited on the iron nail and a chemical reaction
takes place.
2014 - 2015
CHALLENGER
4
CHEMISTRY - CHAPTER SOLUTIONS - 4