Changes Around Us Physical and Chemical

Why is it important to understand physical and chemical changes?

1. They have no practical importance.
2. They help us understand natural processes, industrial applications, and everyday activities.
3. They are useful only in laboratories.
4. They are important only for scientists.

Which of the following is an irreversible change?

1. Freezing water
2. Evaporation of water
3. Burning wood
4. Melting ice

Which statement about physical and chemical changes is correct?

1. Physical changes always form new substances.
2. Chemical changes never form new substances.
3. Physical changes do not form new substances, while chemical changes do.
4. Both changes are exactly the same.

Which method helps prevent rusting of iron?

1. Keeping iron wet
2. Painting or galvanising the surface
3. Breaking the iron into pieces
4. Heating iron continuously

Which process is an example of oxidation?

1. Freezing water
2. Rusting of iron
3. Cutting paper
4. Melting butter

Why is cooking food considered a chemical change?

1. Because food changes colour only
2. Because new substances with different properties are formed
3. Because it can easily become raw again
4. Because only the shape changes

Which gas is commonly required for burning?

1. Nitrogen
2. Oxygen
3. Hydrogen
4. Carbon dioxide

Which of the following is NOT a chemical change?

1. Digestion of food
2. Cooking vegetables
3. Dissolving sugar in water
4. Rusting of iron

What happens when paper burns?

1. It melts into water.
2. It forms new substances such as ash and gases.
3. It only changes shape.
4. It becomes paper again after cooling.

Which observation usually indicates that a chemical change has occurred?

1. Formation of a new substance
2. Change in shape only
3. Change in size only
4. Breaking into smaller pieces

Which of the following is usually reversible?

1. Burning paper
2. Cooking rice
3. Melting ice
4. Rusting iron

Which of the following is a chemical change?

1. Breaking a glass
2. Melting wax
3. Rusting of iron
4. Cutting a piece of cloth

What is a chemical change?

1. A change that forms one or more new substances
2. A change in size only
3. A change in colour only without any new substance
4. A change that is always reversible

Which of the following is an example of a physical change?

1. Rusting of iron
2. Burning of paper
3. Melting of ice
4. Cooking food

What is a physical change?

1. A change that forms a new substance
2. A change in which only the size, shape, or state of a substance changes without forming a new substance
3. A change that always produces heat
4. A change that cannot be reversed