Change around us

What happens when a balloon is blown up and then released?

• It returns to its original shape

• It changes color

• It makes a loud noise

• It floats away

Which of the following changes can be reversed?
a)
b) Melting of ice
c)
d)

• Melting of ice

• Burning of paper

• Cooking of food

• Ripening of mango

What happens when a blacksmith heats a piece of iron?

• It expands and becomes soft

• It breaks into pieces
• It shrinks and becomes harder

• It evaporates into the air

What is the main reason behind heating the iron ring while fixing a wooden handle?

• b) To make the iron ring expand
• a) To increase the weight of the handle
• c) To make the iron ring rust
• d) To improve the grip of the handle

Which of the following is an irreversible change?

• c) Burning a candle completely
• a) Folding a paper into a toy airplane
• b) Boiling water to form steam
• d) Melting wax

Which of these changes occurs when a roti is baked?

• None of the above

• Irreversible

• Reversible

• Temporary

What are reversible and irreversible changes? Give two examples of each.

Describe an activity that shows a reversible change.

Why do road construction workers heat tar before using it? Is this change reversible?

Explain how heating and cooling are used to fix a wooden handle into an iron blade.