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Physical and Chemical Changes
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
(a) Photosynthesis → Chemical change
(b) Dissolving sugar in water → Physical change
(c) Burning of coal → Chemical change
(d) Melting of wax → Physical change
(e) Beating aluminium to make aluminium foil → Physical change
(f) Digestion of food → Chemical change
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
Cutting a log of wood into pieces is a physical change.
(b) False
Formation of manure from leaves is a chemical change.
(c) True
(d) False
Iron and rust are different substances. Rust is iron oxide
(e) True
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 are called physical changes.
(e) Changes in which new substances are formed are called _________changes.
calcium carbonate (CaCO3)
,sodium hydrogen carbonate
,galvanization , painting_
,physical
,chemical
When baking soda is mixed with lemon juice, bubbles are formed with the evolution of a gas. What type of change is it? Explain.
When baking soda (Sodium hydrogen carbonate) is mixed with lemon juice (citric acid), bubbles are formed. The bubbles are formed due to the evolution of carbon dioxide gas. This is a chemical change.
In this change, citric acid contained in lemon juice reacts with sodium hydrogen carbonate which results in the evolution of carbon dioxide gas.
Lemon juice( Citric acid) + Baking soda (Sodium hydrogen carbonate) → Carbon dioxide + Other substances
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Mock Test Series
Mock Test Series