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.
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(ii) Process – B is a chemical change.
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(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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