Class 7 Science - Chapter Physical and Chemical Changes NCERT Solutions | State whether the following statements a
State whether the following statements are true or false. In case a statement is false, write the corrected statement in your notebook.
(a) Cutting a log of wood into pieces is a chemical change. (True/False)
(b) Formation of manure from leaves is a physical change. (True/False) (c) Iron pipes coated with zinc do not get rusted easily. (True/False)
(d) Iron and rust are the same substances. (True/False)
(e) Condensation of steam is not a chemical change. (True/False)
(a) False
This staement is false because cutting the log of wood into pieces is a physical change. Here, no new substances are formed.
(b) False
This staement is false because the formation from manure from leaves is not a physical change. It is the chemical change which involves decomposers and some microorganisms.
(c) True
This staement is true because the coating of zinc protect iron pipe from rusting. It protects the iron pipes to come in contact with air and moisture.
(d) False
This staement is false because iron and rust are the different substances, because rusting occurs when iron is oxidized. Iron is (Fe) and rust is (Fe2O3).
(e) True
This staement is true because condensation of steam is a physical change. Here, no new substances are formed.
More Questions From Class 7 Science - Chapter Physical and Chemical Changes
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Classify the changes involved in the following processes as physical or chemical changes:
(a) Photosynthesis
(b) Dissolving sugar in water
(c) Burning of coal
(d) Melting of wax
(e) Beating aluminium to make aluminium foil
(f ) Digestion of food - Q:-
Describe how crystals of copper sulphate are prepared.
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When baking soda is mixed with lemon juice, bubbles are formed with the evolution of a gas. What type of change is it? Explain.
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Explain how painting of an iron gate prevents it from rusting.
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When a candle burns, both physical and chemical changes take place. Identify these changes. Give another example of a familiar process in which both the chemical and physical changes take place.
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The gas we use in the kitchen is called liquified petroleum gas (LPG). In the cylinder it exist as a liquid. When it comes out from the cylinder it
becomes a gas (Change – A) then it burns (Change – B). The following statements pertain to these changes. Choose the correct one.(i) Process – A is a chemical change.
(ii) Process – B is a chemical change.
(iii) Both processes A and B are chemical changes.
(iv) None of these processes is a chemical change. - Q:-
Explain why burning of wood and cutting it into small pieces are considered as two different types of changes.
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Explain why rusting of iron objects is faster in coastal areas than in deserts.
- Q:-
Fill in the blanks in the following statements:
(a) When carbon dioxide is passed through lime water, it turns milky due to the formation of _________.
(b) The chemical name of baking soda is _________.
(c) Two methods by which rusting of iron can be prevented are _________ and _________.
(d) Changes in which only _________ properties of a substance change re called physical changes.
(e) Changes in which new substances are formed are called _________ changes.
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Name the elements that determine the weather of a place.
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Fill the missing word in the blank spaces in the following statements:
(a) Wind is——————air.
(b) Winds are generated due to —————— heating on the earth.
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Match structures given in Column I with functions given in Column II.
Column I Column II
(i) Stomata (a) Absorption of water
(ii) Xylem (b) Transpiration
(iii) Root hairs (c) Transport of food
(iv) Phloem (d) Transport of water
(e) Synthesis of carbohydrates - Q:-
Fill in the blanks:
(a) Production of new individuals from the vegetative part of parent is called_____________.
(b) A flower may have either male or female reproductive parts. Such a flower is called_____________.
(c) The transfer of pollen grains from the anther to the stigma of the same or of another flower of the same kind is known as _____________.
(d) The fusion of male and female gametes is termed as _____________.
(e) Seed dispersal takes place by means of _____________, _____________ and _____________. - Q:-
Classify the following as motion along a straight line, circular or oscillatory motion:
(i) Motion of your hands while running.
(ii) Motion of a horse pulling a cart on a straight road.
(iii) Motion of a child in a merry-go-round.
(iv) Motion of a child on a see-saw.
(v) Motion of the hammer of an electric bell.
(vi) Motion of a train on a straight bridge. - Q:-
Why do organisms need to take food?
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Explain the role of forest in maintaining the balance between oxygen and carbon dioxide in the atmosphere.
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Mark ‘T’ if the statement is true and ‘F’ if it is false:
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(ii) Plants which synthesise their food themselves are called saprotrophs. (T/F)
(iii) The product of photosynthesis is not a protein. (T/F)
(iv) Solar energy is converted into chemical energy during photosynthesis. (T/F) - Q:-
Match structures given in Column I with functions given in Column II.
Column I Column II
(i) Stomata (a) Absorption of water
(ii) Xylem (b) Transpiration
(iii) Root hairs (c) Transport of food
(iv) Phloem (d) Transport of water
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Tick (✓) mark the correct answer in each of the following:
(a) Fat is completely digested in the
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Which part of the digestive canal is involved in:
(i) absorption of food ________________.
(ii) chewing of food ________________.
(iii) killing of bacteria ________________.
(iv) complete digestion of food ________________.
(v) formation of faeces ________________. - Q:-
Match items in Column I with those in Column II:
Column I Column II
(a) Bud (i) Maple
(b) Eyes (ii) Spirogyra
(c) Fragmentation (iii) Yeast
(d) Wings (iv) Bread mould
(e) Spores (v) Potato
(vi) Rose - Q:-
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(i) concave lens (ii) concave mirror
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Match the items in Column I with those in Column II:
Column I Column II
(a) Yeast (i) Earthworm
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(d) Leaves (iv) Chest cavity
(e) Fish (v) Stomata
(f) Frog (vi) Lungs and skin
(vii) Tracheae
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