The DAV Class 6 Science Solutions and DAV Class 6 Science Chapter 5 Question Answer – Changes Around Us are essential study tools for DAV public school students in Class 6.
DAV Class 6 Science Ch 5 Question Answer – Changes Around Us
DAV Class 6 Science Ch 5 Solutions – Changes Around Us
Something To Know
A. Fill in the blanks.
Question 1.
All irreversible changes bring a ______ change in a substance.
Answer:
permanent
Question 2.
A change, in which the substance produced can get back to the original form, is called a ______change.
Answer:
reversible
Question 3.
Bending of an iron rod is a ______ change.
Answer:
physical
Question 4.
Burning of fuel is a ______ chemical change, whereas rusting of iron is a ______ chemical change.
Answer:
fast, slow,
Question 5.
In chemical change, new substances with ______ properties are formed.
Answer:
new
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 of milk into curd is a physical change.
Answer:
1. Glowing of an electric bulb is a fast change. (True)
2. Deforestation is a reversible change. (False)
3. Burning of paper is a temporary change. (False)
4. Cutting of an apple is a chemical change. (False)
5. Making of fruit salad is a chemical change. (False)
6. Changing of milk into curd is a physical change. (False)
C. Tick (✓) the correct option.
1. Which of the following can be considered as a fast change?
(a) Growth of a child
(b) Germination of seeds
(c) Bursting of a firecracker
(d) Cooking of food
Answer:
(c) Bursting of a firecracker
2. Evaporation of water is a
(a) Physical change
(b) Fast change
(c) Irreversible change
(d) Chemical change
Answer:
(a) Physical change
3. Which one of these changes is a reversible change?
(a) Burning of a candle
(b) Inflating a balloon
(c) Baking of chapatti
(d) Grinding of wheat grains into flour
Answer:
(b) inflating a balloon
4. Which one of these is an irreversible change?
(a) Growth of a child
(b) Stretching a rubber band
(c) Evaporation of water
(d) Formation of ice from water
Answer:
(a) Growth of a child
5. A piece of paper undergoes a chemical change when it is
(a) Cut
(b) Folded
(c) Reshaped into a paper toy
(d) Burned
Answer:
(d) Burned
D. Answer the following questions in brief.
Question 1.
Define the following terms.
(a) Reversible change
Answer:
Some changes can be reversed by removing the cause of the change. Such changes are called reversible change.
(b) Chemical change
Answer:
A change in which a new substance is formed is called chemical change.
(c) Physical change
Answer:
A change in which no new substance is formed is called physical change.
Question 2.
Distinguish between fast and slow changes. Give two examples of each type.
Answer:
| Fast change | Slow change |
| Happens in short duration. | Happens in long duration. |
| Examples: burning of paper, bursting of firecracker | Examples: movement of earth, growth of a tree |
Question 3.
Give two examples of reversible and irreversible changes.
Answer:
| Reversible change | Irreversible change |
| Inflating a balloon, melting of ice | Cooking of food, germination of seeds |
Question 4.
State some of the irreversible biological changes that take place in nature. Answer:Growth of a child, growth of a tree, germination of seeds, ripening of fruits, etc.
Question 5.
Give an example of a physical change in which
1. energy is given out
2. energy is absorbed.
Answer:
- Glowing of bulb is a physical change in which heat is given out.
- Melting of ice is a physical change in which heat is absorbed.
E. Answer the following questions.
Question 1.
Give two differences between reversible and irreversible changes.
Answer:
| Reversible change | Irreversible change |
| Can be reversed. | Cannot be reversed. |
| Most of the reversible changes are physical changes. | Most of the irreversible changes are chemical changes. |
| Examples: Inflating a balloon, melting of ice | Examples: Cooking of food, germination of seeds |
Question 2.
‘Formation of curd is an irreversible and chemical change’. Justify this statement.
Answer:
During formation of curd from milk, a new substance is formed. Moreover, once milk changes into curd, it cannot be changed back into milk. Hence, it can be said that formation of curd is an irreversible and chemical change.
Question 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:
During water cycle, the physical form of water changes and no new substance is formed hence it is a physical change. Water can be changed into its different form hence it is a reversible change.
Question 4.
How can we say that burning of candle is a chemical change and glowing of bulb is a physical change?
Answer:
During the burning of candle, new substances are formed hence it is a chemical change. During the glowing of bulb, no new substance is formed hence it is a physical change.
Value Based Questions
Madam Emani, a very sincere and dedicated teacher, had a very honest, considerate and understanding approach towards the problems of her students. This helped her to make her students improve their performance and become better persons. Her school principal would often say, “The changes, brought about by Madam Emani, are quite similar to those that occur during a chemical change.”
Question 1.
State the values that helped Madam Emani become a popular teacher.
Answer:
Honesty, empathy, friendliness
Question 2.
State with reason, whether you agree or disagree with the principal’s statement.
Answer:
The changes brought by Madam Emani are permanent in nature. Hence, teacher is making the right comment.
Question 3.
Have a ‘group discussion’ in which one student suggests a possible change’ (like a change in the section of the class) and the other students think of the likely effects of that change.
Answer:
Do it yourself.
Something To Do
Question 1.
Solve the puzzle with the help of clues given below.
Across
(a) A change which cannot be reversed,
(b) A metal which gets rusted.
(f) An example of a chemical change in which energy is released.
Down
(c) A change in which original condition can be re-attained.
(d) The change which takes place in long duration of time,
(e) A reversible change involving change of liquid into gas.
Answer:
Question 2.
Go to your neighbourhood and make a list of all the changes you observe, such as setting of sun, burning of leaves, etc. Also, classify these as slow/fast; reversible/ irreversible and controllable/uncontrollable. Record your observations in a tabular form.
Answer:
| Change | Slow/fast | Reversible/ Irreversible | Controllable/ uncontrollable |
| Setting of sun | Slow | Irreversible | Uncontrollable |
| Burning of leaves | Fast | Irreversible | Controllable |
| Cooking of food | Slow | Irreversible | Controllable |
| Melting of ice | Slow | Reversible | Controllable |
| Inflating a balloon | Fast | Reversible | Controllable |
Question 3.
Take two test tubes, half filled with water. To the first test tube, add salt and to the second add quicklime. What do you observe? Is there a release of energy? Comment.
Answer:
In the first test tube, salt is dissolved in water. There is no change in temperature of test tube. In the second test tube, quicklime is dissolved in water. The test tube becomes hot. This shows that energy is released during this change.
DAV Class 6 Science Chapter 5 Solutions – Changes Around Us
I. Fill in the blanks.
Question 1.
A ______ change takes too much time.
Answer:
Slow
Question 2.
A ______ change takes too little time.
Answer:
Fast
Question 3.
No new substance is formed after a ______ change.
Answer:
Physical
Question 4.
A new substance is formed after a ______ change.
Answer:
Chemical
Question 5.
______ of wax is a physical change.
Answer:
Melting
Question 6.
______ of candle is a chemical change.
Answer:
Burning
Question 7.
When iron reacts with atmospheric moisture and air, ______of iron takes place.
Answer:
Rusting
Question 8.
Formation ______ from milk is a fast change.
Answer:
Cheese
Question 9.
Formation of ______ from milk is a slow change.
Answer:
Curd
Question 10.
______ of bulb is a reversible change.
Answer:
Glowing
II. Tick (✓) the correct option.
1. Which of the following is a fast change?
(a) Germination of seed
(b) Weathering of rock
(c) Melting of ice
(d) Growth of a child
Answer:
(c) Melting of ice
2. Which of the following is a slow change?
(a) Melting of wax
(b) Burning of candle
(c) Glowing of bulb
(d) Rusting of iron
Answer:
(d) Rusting of iron
3. Heat is absorbed during which of the following
(a) Freezing of water
(b) Melting of ice
(c) Burning of candle
(d) All of these
Answer:
(b) Melting of ice
4. Which of these is a desirable change?
(a) Germination of seed
(b) Flood
(c) Rusting of iron
(d) Breaking of glass tumbler
Answer:
(a) Germination of seed
5. Which of these is an undesirable change?
(a) Formation of cloud
(b) Glowing of bulb
(c) Melting of ice cream
(d) Cooking of food
Answer:
(c) Melting of ice cream
6. Heat is released during which of these changes?
(a) Melting of wax
(b) Burning of candle
(c) Evaporation of water
(d) Rusting of iron
Answer:
(b) Burning of candle
7. Which of these is an irreversible change?
(a) Boiling of water
(b) Formation of ice
(c) Formation of frost
(d) Formation of curd
Answer:
(d) Formation of curd
III. Answer these questions.
Question 1.
What is a slow change? Explain with the help of an example.
Answer:
The time required for some changes is too much. Such changes are called slow changes. For example, formation of curd from milk takes at least four to five hours and hence it can be termed as a slow change.
Question 2.
What is a physical change? Give an example of physical change.
Answer:
A change in which no new substance is formed is called physical change. Most of the physical changes are reversible. For example, during melting of ice, no new substance is formed rather just the physical state of water changes.
Question 3.
What is a chemical change? Give an example of chemical change.
Answer:
A change in which no new substance is formed is called chemical change. Most of the chemical changes are irreversible. Some chemical changes can be reversed by using chemical meAnswer:For example, during burning of paper, the paper turns into ash and carbon which cannot be changed back to paper.
Question 4.
What is the difference between desirable and undesirable change?
Answer:
When a change is beneficial for us, it is called a desirable change, but when a change is harmful for us, it is called an undesirable change.
Question 5.
What is a chemical reaction?
Answer:
A change during which a new substance is formed is called a chemical change or chemical reaction.
Question 6.
Moulding of clay is a physical change but baking a clay pot is a chemical change. How?
Answer:
When clay is moulded into a particular shape, no new substance is formed and it can be remoulded into another shape or into a lump of clay. But when a clay pot is baked, a new substance is formed which cannot be changed back into clay. Hence, moulding of clay is a physical change, while baking of a clay pot is a chemical change.
IV. Projects
Question 1.
Burn a candle and identify various types of changes taking place during this. Also make a list of new substances; if any; formed during the change.
Answer:
Do it yourself.
Question 2.
Make a flow chart of ice changing into water which changes into vapour and finally back to ice. Mark the steps where heat is absorbed and evolved.
Answer:
Do it yourself.