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SAI INTERNATIONAL SCHOOL
CLASS-VII
SUBJECT- CHEMISTRY
TOPIC-PHYSICAL AND CHEMICAL CHANGES
SUB TOPIC- CRYSTALLISATION

Practice Worksheet-3

Q. No. Questions Skill Marks

1. Fill in the blanks: u 1
Rusting can be prevented by................ and........................

2. Write True/ False for the following statement. U 1
Copper can displace iron from iron sulphate solution.

3. Choose the correct option from the following: K 1
a) If both Assertion and Reason are correct and Reason is
the correct explanation of Assertion.
b) If both Assertion and Reason are correct, but Reason is
not the correct explanation of Assertion.
c) If Assertion is correct but Reason is incorrect.
d) If Assertion is incorrect but Reason is correct.
e) If Assertion & Reason both are incorrect.
Assertion (A): A saturated solution is that in which no more
solute can be dissolved.

Reason (R): Crystallisation can be done using saturated and
unsaturated both types of solution.

4. a) The decomposition of animal waste by an anaerobicbacteria U & A 1+2
produces bio gas (Change-A). The bio gas is then use as fuel
(Change-B). Mention the types of changes.
b) What is the differences between them?

5. a) In which city do you expect rusting of an iron article to be a Hots a)
greater problem inLucknow or Mumbai? Why? 2+1
b) 1
b) What will be the observation if the article has kept on moon.
c) 1

c)Compare the degree of rusting in three places.

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