Science Notes 5th Class Unit No.5

UNIT NO.5

Physical and Chemical Changes of Matter

(Solved Exercise)

1. Choose the correct answer.
i. Butter going soft on a hot day is an example of
a. melting
b. freezing
c. boiling
d. evaporation

ii. Which of these is not the result of chemical change?
a. boiled egg
b. rusted nail
c. bread
d. freezing water

iii. Which of these is an example of a physical change?
a. tearing of paper
b. burning of paper
c. burning of wood
d. cooking meat

iv. Chemical changes are usually
a. reversible
b. irrepressible
c. irreversible
d. invisible

v. Clouds are formed by
a. hot air rising.
b. water vapour condensing
c. boiling.
d. rain falling.

2. Fill in the blanks.
i. On absorbing heat, a solid changes into a gas. This process is known as Sublimation.
ii. Upon cooling, a gas changes into liquid. This process is known as Condensation.
iii. A change of state is also known as a physical change.
iv. Ice is the Solid state of water.

3. Answer these questions.
i. What do you understand by physical change? Give three examples of physical changes taking place in your environment.
Answer:
Physical Change
A physical Change is when a material is changed but the chemical nature of is not changed.
Example:
• Melting ice
• Tearing of paper
• Dissolving salt in water
ii. Describe three different states of water. Draw diagrams.
Answer:
Solid
In Solid State particles of solid are close to each other.
Liquid
In liquid State of particles have spaces but no attraction between them.
Gas
In gas form particles move freely and have more space between them.

iii. What is the difference between strong and weak concentrations of simple solutions?
Answer:

4. Differentiate between physical and chemical changes.