Page 1 - CBW

SAI International School

Competency Based Worksheet
Subject – Chemistry

Chapter – Physical and Chemical Changes

Class- VII

Q. No. Questions

1. You left an iron nail in the open air and it turned reddish-brown. Which conclusion is
correct?
(a) It is a physical change because the shape remains same
(b) It is a chemical change due to formation of a new substance (rust).
(c) It is reversible, so it is a physical change
(d) It is a temporary chemical change

2. Why is cutting vegetables considered a physical change?
(a) It changes the taste of vegetables
(b) It cannot be reversed
(c) It changes the size and shape but no new substance is formed
(d) It changes the chemical composition

3. Which of the following pairs includes one physical and one chemical change?
(a) Boiling of water and melting of wax
(b) Melting of ice and tearing of paper
(c) Rusting of iron and condensation of water vapour
(d) Burning of wood and formation of curd

4. student heats sugar in a test tube. It turns black and gives off fumes. What kind of change
has occurred?
(a) Only a physical change
(b) Only a chemical change
(c) Both physical and chemical changes
(d) No change has occurred

5. Why is the setting of cement is considered a chemical change?
(a) It involves a temperature change
(b) It can be reversed
(c) New substances are formed and the change is permanent
(d) It involves only a change in state

Choose the correct option for the following: (For questions- 6 and 7)
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.