Class Work Assignment
Extra Question
Q1. Differentiate between Reversible and irreversible changes.
Ans. Reversible Change :- Changes in which the objects and the materials can be obtained back in their original form.
Irreversible Change:- Changes from which we cannot get materials or objects back in their original form.
Q2.Differentiate between Physical change and Chemical change.
Ans. Physical change:- A change in which no new substance is formed and the properties of the remains same. For example :- Changing water into ice.
Chemical change:- A change in which new substance is formed and the properties of the substance is changed. For examples:- Burning of wood.
Q3.Explain how a metal rim is fixed around the wooden wheel of a cart. What type of change takes place during this process?
Ans. The metal rim is made slightly smaller than the wooden wheel. On heating the rim it expands and fits into the wheel. Cold water is then poured over the rim which contract sand fits into the wheel. This is a reversible change.