A physical change differs from a chemical change in that ______________________________ are formed.
Answers
Answer:
Sugar dissolving in water is a physical change. The sugar can be obtained back by evaporation of water and the water by condensation of water vapour.
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Question 1:
Give one example for each of the following types of changes:
(a) physical changes.
(b) chemical changes
(c) reversible changes
(d) irreversible changes
ANSWER:
(a) Physical changes:
Example: Change in the size of the pencil or eraser with continuous use.
(b) Chemical changes:
Example: Burning of wood.
(c) Reversible changes:
Example: Salt dissolving in water.
(d) Irreversible changes:
Example: Curdling of milk.
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Question 2:
A potter shapes pots out of clay. He then bakes the pots in an oven. Identify the reversible and irreversible changes taking plance in the process.
ANSWER:
A potter shapes pots out of clay. This is a physical change which can be easily reversed. During this change, only the shape of the substance changes, without any change in the texture of the clay.
The potter then bakes the pots in an oven that makes the clay to becomes hard and brittle. Thus, there is a change in the internal structure of clay which makes soft clay hard and brittle. This is a chemical change which is irreversible
Explanation:
In a physical change the appearance or form of the matter changes but the kind of matter in the substance does not. However in a chemical change, the kind of matter changes and at least one new substance with new properties is formed.