Question 1.7 - Chemistry: Molecular Nature Of Matter And Change

Question

Which of the following changes can be reversed by changing the temperature: (a) dew condensing on a leaf; (b) an egg turning hard when it is boiled; (c) ice cream melting; (d) a spoonful of batter cooking on a hot griddle?

Step-by-Step Solution

Answer

Answer

Physical changes are ice cream melting and dew condensation, which can be reversed by temperature change. 

Types of changes

The change in which there is no formation of new chemical  bonds is called a physical change. There is only a change in the physical property where there is no change in composition.

The change in which the creation of new compounds occurs is called a chemical change.

Type of change

a. The water on a leaf evaporates when the temperature rises. The reverse process is condensation and evaporation. Dew condensing on the leaf is a physical change and reversible by changing temperature.

 

b. It is irreversible that the reaction can happen when egg boiling. Turning of egg hard when boiled is irreversible by temperature change.

 

 

c. There is a physical change when the temperature becomes low, turning ice cream into solid. There is a reverse reaction by temperature change is melting of ice cream.

 

d. It is irreversible by temperature change. A chemical change is batter cooking.