Page 2 - CBW

Reason (R): The process used to separate grain from stalks is known as winnowing.

8. A student uses a sieve to separate a mixture of rice and stones. Explain why this method is
effective and what properties of the substances are being utilized.

9. Fill in the blanks:

a) The process of separating seeds of paddy from its stalks is called ___________.
b) A mixture of mustard oil and water can be separated by using a ___________.
10. Case Description: Gourav is helping his mother in the kitchen, and she asks him to
separate small pieces of stones from a bowl of rice.
Questions:
1) Describe how Gourav can use handpicking to separate stones from rice. What conditions
make handpicking suitable for this task?
2) Explain the process of sieving and how it can be used to separate substances. What type of
materials can be separated effectively through sieving?
3) What is the primary condition that makes handpicking effective for separating substances?

11. Case Description : In a rural village, farmers harvest paddy and need to separate the rice grains
from the husk. They use a traditional method involving wind.
Questions:
1. What is the name of the method used by the farmers to separate rice grains from the
husk?
2. Why is winnowing an effective method for this separation?

12. Observe the picture carefully and answer the following
questions :

(a) Identify the apparatus shown in the picture.

(b) What is the primary property that allows the
use of this process ?

(c) Which of the following mixtures can be
separated using this process ?

(i) Sugar and water

(ii) Salt and water

(iii) Oil and water

(iv) Alcohol and water

13. Why is it important to separate mixtures?

14. Name the following:
a. The two types of pure substances-
b. Separating lighter particles from heavier ones by blowing air through the mixture.

15. What is the role of alum in water purification?