Chemical Changes and Its Characteristics

Q.

How do you know that chemical change has taken place?

Q. A slice of apple acquires a brown colour if it is not consumed immediately, explain.

Q.

Classify the following in physical or chemical change.

Dissolving zinc metal in hydrochloric acid.

Q.

Classify the following changes into physical and chemical change:

Rotting of egg

Q.

Melting of ice is a periodic change

1. True
2. False

Q.

Differentiate between the following changes with suitable examples.

b. Reversible and irreversible changes

Q. Burning of wood and rusting of iron bar are examples of ___________ changes.

1. physical and chemical
2. physical
3. chemical
4. biological

Q. Burning of wood and rusting of iron bar are examples of ________ changes.

1. periodic
2. temporary
3. physical
4. chemical

Q. Burning of wood and rusting of iron bar are examples of ________ changes.

1. chemical
2. periodic
3. temporary
4. physical

Q. Burning of wood and rusting of iron bar are examples of ___________ changes.

1. physical
2. chemical
3. biological
4. physical and chemical

Q.

The general day to day activities of a primary school going teen named Swami are mentioned below.
1. To walk through a waterlogged area, Swami shortens the length of his dress by folding it.
2. In school, he draws an apple in his slate with chalk.
3. After school, he comes home directly and starts playing with his new toy, but accidently breaks it.
4. At night, his mother cooks food for him. He eats and then goes to bed.
Connect the above excerpts to a reversible or an irreversible change.

1. Reversible change - 1, 2, 3, 4; Irreversible change - NA

2. Reversible change - 1, 2; Irreversible change - 3, 4

3. Reversible change - 3, 4; Irreversible change - 1, 2

4. Reversible change - NA; Irreversible change - 1, 2, 3, 4

Q.

A change cannot be

1. Irreversible

2. If their is no alteration in the state.

3. Reversible and irreversible

4. Reversible

Q. Identify the following as physical or chemical change. [6 marks]

Q. When baking soda is mixed with lemon juice, bubbles are formed with the evolution of a gas. What type of change is it? Explain. (2 marks)

Q.

Heating will produce what sort of change?

1. A reversible change

2. An irreversible change

3. Either a reversible or irreversible change

4. Neither a reversible or irreversible change

Q. Which of the following change is not observed during curdling of milk?

1. State
2. Weight
3. Taste
4. Colour

Q. Reversible change refers to a change that can be undone.

1. False
2. True

Q.

Classify the following processes into physical or chemical changes:

(i) Beating of aluminium metal to make aluminium foil.
(ii) Digestion of food.
(iii) Cutting of a log of wood into pieces.
(iv) Rusting of iron.

Q. Reversible change refers to a change that can be undone.

1. False
2. True

Q.

Which of the following changes indicate that a chemical change has not been taken place?

1. No new substance is formed
2. Absorption or release of heat
3. Change in colour
4. Evolution of gas

Q. ____ change is involved in the given image:

1. Natural
2. Reversible
3. Physical
4. Chemical

Q. ____ change is involved in the given image:

1. Chemical
2. Natural
3. Reversible
4. Physical

Q.

Which of the following is an example of reversible change?

1. Molding clay to form a toy

2. Making a light mark on a paper with a pencil

3. Cutting a piece of paper

4. Ripening of fruits

Q. The general day to day activities of a primary school going teen named Swami are mentioned below.
1. To walk through a waterlogged area, Swami shortens the length of his dress by folding it.
2. In school, he drew an apple on his slate with chalk.
3. After school, he directly came back to his home and started playing with his new toy, but accidentally it broke.
4. At night, his mother cooked food for him. He ate and then retires to bed.
Connect the above excerpts to reversible or irreversible change.

1. Reversible change - 1, 2, 3, 4; Irreversible change - NA

2. Reversible change - 1, 2; Irreversible change - 3, 4

3. Reversible change - 3, 4; Irreversible change - 1, 2

4. Reversible change - NA; Irreversible change - 1, 2, 3, 4

Q.

Classify the following processes into physical or chemical changes:

(i) Beating of aluminium metal to make aluminium foil.
(ii) Digestion of food.
(iii) Cutting of a log of wood into pieces.
(iv) Rusting of iron.

Q. Which of the following is an example of reversible change?

1. Molding clay to form a toy
2. Making a light mark on a paper with a pencil
3. Cutting a piece of paper
4. Ripening of fruits

Q. Burning of wood and rusting of iron bar are examples of ___________ changes.

1. physical and chemical
2. biological
3. physical
4. chemical

Q.

In any situation, a change can be

1. where there is no alteration in state.

2. Irreversible

3. Reversible

4. Both reversible and irreversible

Q. Which of the following substances will show a chemical changes when kept in open for a few days?

1. Pizza
2. Milk
3. Camphor balls
4. Pickle

Q.

By giving a reason state why chemical change takes place in the following case:

Formation of biogas (gobar gas)