2. Complete Activity 5.2 (Page 47). Collect the chalk dust lying on the floor near the chalkboard in your classroom. Or, crush a small piece of chalk into dust. Add a little water to the dust to make a paste. Roll it into the shape of a piece of chalk. Let it dry. Did you recover chalk from the dust?
Answer:
The above activity can be carried out as follows:
Aim: To try to recover chalk from the dust and conclude based on what you observe.
Materials Required: Chalk dust, water.
Procedure:
(i) Collect some chalk dust lying on the floor near the chalkboard in the classroom or crush a small piece of chalk into dust.
(ii) Add a little water to the dust and stir it to form a paste.
(iii) Now try to roll the paste into the shape of the piece of chalk and let it dry.
Observations:
On drying the paste forms a chalk.
Conclusions:
There is only change in the shape and size of the chalk. These are physical properties and thus the change is a physical change.
“Complete Activity 5.2 (Page 47). Collect the chalk dust lying on the floor near the chalkboard in your classroom. Or, crush a small piece of chalk into dust. Add a little water to the dust to make a paste. Roll it into the shape of a piece of chalk. Let it dry. Did you recover chalk from the dust?” – Solved.
Related Links:
Solution to Extended Learning – Activities and Projects Question 1
Solution to Extended Learning – Activities and Projects Question 2
Solution to Extended Learning – Activities and Projects Question 3
Solution to Extended Learning – Activities and Projects Question 4
Solution to Activity 5.1
Solution to Activity 5.3
Solution to Activity 5.4
Solution to Activity 5.5
Solution to Activity 5.6
Solution to Activity 5.7
Solution to Activity 5.8
Solutions to Chapter 5 Physical and Chemical Changes
