DAV Class 6 Science Book Solution Chapter 5

DAV Class 6 Science Book Solution Chapter 5 Changes Around Us are prepared by subject experts. DAV Solutions have answers to variety of questions, which will help you to gain knowledge on the types of questions that can be asked on the topic.

DAV Class 6 Science Book Solution Chapter 5 Changes Around Us

Highlights

• A. Fill in the blanks.
• B. True or False.
• C. Tick the correct option.
• D. Answer the following questions in brief.
• E. Answer the following questions.

A. Fill in the blanks.

1. All irreversible changes bring a ___________ change in a substance.

2. A change, in which the substance produced can get back to the original form, is called a ___________ change.

3. Bending of an iron rod is a ___________ change.

4. Burning of fuel is a ___________ chemical change, whereas rusting of iron is a ___________ chemical change.

5. In chemical change, new substances with ___________ properties are formed.

Answer: (1) permanent (2) reversible (3) physical (4) fast, slow (5) different

B. Write True or False for the following statements.

1. Glowing of an electric bulb is a fast change.

2. Deforestation is a reversible change.

3. Burning of paper is a temporary change.

4. Cutting of an apple is a chemical change.

5. Making of fruit salad is a chemical change.

6. Changing milk into curd is a physical change.

Answer: (1) True (2) False (3) False (4) False (5) False (6) False

C. Tick the correct option.

Answer:

D. Answer the following questions in brief.

1. Define the following terms.

(a) Reversible change

(b) Chemical change

(c) Physical change

Answer:

(a) Reversible change – a change, in which substance produced, can be brought back into its original form.

(b) Chemical change – a change, in which a new substance, is formed.

(c) Physical change – a change, in which no new substance, is formed.

2. Distinguish between fast and slow changes. Give two examples of each type.

Answer:

Fast changes – The changes, that take place quickly, or in a shorter duration of time, are called fast changes.

Two examples of fast changes are: burning of a paper and lighting of a bulb.

Slow changes – The changes, that take place in a longer duration of time, are called slow changes.

Two examples of slow changes are: change of seasons and growth of a plant.

3. Give two examples each of reversible and irreversible change.

Answer:

4 State some of the irreversible biological changes that take place in nature.

Answer: Ripening of fruits, change of seasons, growth of a child and growth of plants are some of the irreversible biological changes that takes place in nature.

5. Give one example of a physical change in which (i) energy is given out (ii) energy is absorbed.

Answer:

(1) glowing of bulb.

(2) melting of ice.

E. Answer the following questions.

1. Give two differences between reversible and irreversible changes.

Answer: two differences between reversible and irreversible changes are-

Reversible Change:

• 1. A change, in which the substance produced can get back to the original form, is called a reversible change.
• 2. These are temporary changes which can be reversed when the cause of the change is removed. Example: evaporation.

Irreversible Change:

• 1. A change, in which the substance produced cannot get back to the original form, is called an irreversible change.
• 2. These are permanent changes which cannot be reversed even if the cause of the change is removed. Example: making curd from milk.

2. ‘Formation of curd is an irreversible as well as a chemical change.’ Justify this statement.

Answer: Formation of curd is an irreversible change because we cannot change curd back into milk. Also, it is a chemical change because new substance that is curd is formed with different property.

3. Water cycle is a natural change. Classify it as a (i) physical or chemical change (ii) a reversible or irreversible change. Also, justify your answer.

Answer:

(1) Water cycle is a natural change and it is also, a physical change because no any new substance is formed, only appearance and physical state is change.

(2) Water cycle is a natural change and it is also a reversible change because in this change water change into vapour state and again change from vapour into liquid state.

4. How can we say that burning of candle is a chemical change but the glowing of bulb is a physical change?

Answer:

We can say that burning of candle is a chemical change because when a candle is burning it gives us light, heat, and smoke which is a new property. On the other hand, glowing of bulb is a physical change because no new substance is formed, only appearance of bulb is change. So, we can say that it is a physical change.

Important topics covered in DAV Class 6 Science Book Solution Chapter 5 Changes Around Us

• Slow and Fast Changes
• Reversible and Irreversible Changes
• Physical and Chemical Changes
• Changes Involve Energy

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