DAV Class 6 Science Solution Chapter 5 Changes Around Us
DAV School Books Class 6 Science Solution Chapter 5 Changes Around Us all Question Answer. DAV Class 6 5th Chapter Changes Around Us full Chapter explanation by expert teacher.
DAV School Books Class 6 Science Solution Chapter 5 Changes Around Us:
(A) Fill in the blanks.
Answer:- (1) chemical
Answer:- (2) Reversible.
Answer:- (3) reversible.
Answer: (4) irreversible, irreversible.
Answer:- (5) chemical.
(B) Write True or False for the following statements.
Answer: (1) True.
Answer: (2) False.
Answer: (3) False.
Answer: (4) False.
Answer: (5) False.
Answer: (6) False.
(C) Tick (✓) the correct option.
(1) Which of the following can be considered as a fast change?
Answer: (c) Bursting of firecracker.
(2) Evaporation of water is a ______.
Answer: (a) Physical change.
(3) Which one of these changes is a reversible change?
Answer:- (b) Inflating a balloon.
(4) Which one of these is an irreversible change?
Answer:- (a) Growth of child.
(5) A piece of paper undergoes a chemical change, when it is
Answer:- (d) Burned.
(D) Answer the following questions in brief.
(1) Define the following terms.
(a) Reversible change
(b) Chemical change
(c) Physical change
Answer:-
(A) The change in which, the formed product is converted into the original product is called reversible change.
(B) A change in which new substance is formed is called chemical change.
(C) A change in which no new substance is formed is called physical change.
(2) Distinguish between fast and slow changes. Give two examples of each type.
Answer:-
- Fast changes – A change that happens in fast duration is called fast changes.
- Example – cooking, burning paper.
- Slow changes – A change can happen in slow or long duration is called slow changes.
- Example – body growth, rusting
(3) Give two examples each of reversible and irreversible change.
Answer:
Reversible change Examples –
(1) Stretching of rubber band.
(2) melting of wax.
Irreversible change Examples –
(1) Burning of fuel and wood.
(2) Cooking food.
(4) State some of the irreversible biological changes that take place in nature.
Answer:- Some irreversible biological changes are – burning of wood, growth of living organisms, changes of season, ripening of fruit, turning of milk into curd.
(5) Give one example of a physical change in which (i) energy is given out (ii) energy is absorbed.
Answer:-
Energy is given out – consuming food, blowing lights. Energy is absorbed – boiling water, cooking.
(E) Answer the following questions.
(1) Give two differences between reversible and irreversible changes.
Answer:-
Two differences between reversible and irreversible change are –
(A) Reversible change The process in which a formed product is converted into an original product is called reversible change. Reversible change is a temporary change. Example – streching of rubber
(B) Irreversible change – The process in which the formed product is not converted into the original product is called irreversible change. Irreversible change is permanent change Example – burning of fuel
(2) ‘Formation of curd is an irreversible as well as a chemical change.’ Justify this statement.
Answer:- Formation of curd from milk is an irreversible change because the curd cannot be converted back into milk. And the curd formed is with the new 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:- The water cycle is a natural change but then also it’s reversible change because the cycle is continuing like the water is evaporated, forms cloud and again converted into water in the form of rain Water cycle is physical change also because no new substance is formed
(4) How can we say that burning of candle is a chemical change but the glowing of bulb is a physical change?
Answer:- When a candle burns it gives heat, light which is a chemical change. But when the bulb blows there is no formation of new substance therefore it is physical change.
Value based questions
Q.) 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.”
(1) State the values that helped Madam Emani become a popular teacher.
Answer:- Madam Emani was very honest, sincere, dedicated and understanding teacher. She always helps students.
(2) State with reason, whether you agree or disagree with the principal’s statement.
Answer:- I agree with this statement, because once you became a good teacher and teaches students good things then it cannot be changed like chemical change.
(3) Have a ‘group-discussion’ in which one student suggests a possible ‘change’ (like a change of the section of the class) and the other students think of the likely effects of that change.
Answer:- If the section of classes are changed, then it’s helpful, because you feel sociable and have a large circle of friends.
Something To Do
(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:-
1.) Slow change:- growth of plants, growth of children, etc.
2.) Fast change:- throwing a ball, filling water bottle, etc.
3.) Reversible change:- folding of paper, cleaning house, etc.
4.) Irreversible change:- burning a candle, tearing paper, etc.
5.) Controllable change:- opening the door, increasing the speed of the car, etc.
6.) Uncontrollable change:- formation of rainbow, growth of plants.
(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:- When we add quicklime to second test tube that time heat realise out and exothermic reaction take place calcium oxide reacts with water and there is formation of calcium hydroxide and test tube become hot.
CaO+H2O → Ca(OH)2+heat
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