6th Science Guide Term 2 Lesson 3 Changes Around Us
6th Standard Science Term 2 Book Back Answers Lesson 3 Changes Around Us – English Medium
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6th Science Guide Term 2 Lesson 3 Changes Around Us
I. Choose the correct answer:
1. When ice melts to form water, change occurs in its
- position
- colour
- state
- composition
Ans : state
2. Drying of wet clothes in air is an example of
- Chemical change
- Undesirable change
- irreversible change
- physical change
Ans : physical change
3. Formation of curd from milk is
- reversible change
- a fast change
- an irreversible change
- an undesirable change
Ans : an irreversible change
4. Out of the following an example of a desirable change is
- rusting
- change of seasons
- earthquake
- flooding
Ans : change of seasons
5. Air pollution leading to Acid rain is a
- reversible change
- fast change
- natural change
- human made change
Ans : human made change
II. Fill in the blanks
- Magnet attracts iron needle. This is __________________ change. (a reversible / an irreversible) Ans : a reversible
- Boiling of egg results in __________________ change. (a reversible / an irreversible) Ans : an irreversible
- Changes that are harmful to us are __________________. (desirable / undesirable) Ans : undesirable
- Plants convert Carbon-di-oxide and water into starch. This is an example of change. __________________ (natural / human made)Ans : natural
- Bursting of fire crackers is a change whereas germination of seeds is a change __________________ . (slow / fast)Ans : fast
III. True or False. If False, give the correct statement
- Growing of teeth in an infant is slow change.Ans : True
- Burning of match stick is a reversible changeAns : False
- An : Burning of match stick is irreversible change
- Change of New moon to Full moon is human made.Ans : False
- An : Change of New moon to Full moon is Natural made
- Digestion of food is a physical change.Ans : False
- An : Digestion of food is a chemical change
- In a solution of salt in water, water is the soluteAns : False
- An : In a solution of salt in water ,water is the solvent
IV. Analogy
1. Curdling of milk : irreversible change :: Formation of clouds : ________change
Ans : reversible
2. Photosynthesis : __________ change :: burning of coal : Human – made change
Ans : natural made
3. Dissolving of glucose : reversible change :: Digestion of food: ___________ change
Ans : irreversible
4. Cooking of food : desirable change :: decaying of food : _________change
Ans : undesirable
5. Burning of matchstick :_______ change: Rotation of the Earth : Slow change
Ans : fast
V. Circle the odd one out. Give reason for your choice
1. Growth of a child, Blinking of eye, Rusting, Germination of a seed
Ans : Rusting
- Reason : Rusting is chemical change others are slow change
2. Glowing of a bulb, lighting of a Candle, breaking of a coffee mug, curdling of milk
Ans : curdling of milk
- Reason : curdling of milk irreversible change others are fast change
3. Rotting of an egg, condensation of water vapour, trimming of hair, Ripening of fruit
Ans : Rotting of an egg
- Reason : Rotting of an egg is Undesirable change others are slow change
4. Inflating a balloon, popping a balloon, fading of wall paint, burning of kerosene
Ans : fading of wall paint
- Reason : fading of wall paint is slow change others are fast change
VI. Give very short answer
1. What kind of a change is associated with decaying of a plants?
- decaying of a plants is natural change.
2. You are given some candle wax. Can you make a candle doll from it? What kind of change is this?
- Yes, reversible change.
3. Define a slow change.
- Changes which take place over a long period of time ( hours / days / months / years ) are known as Slow changes.
4. What happens when cane sugar is strongly heated? Mention any two changes in it.
- water molecule evaporated from the canesugar charring occours Irreversible change and chemical change.
5. What is a solution?
- solute is dissolved in a solvent it forms a solution
VII. Give short answer
1. What happen when paper is burnt? Explain.
- Changes which take place within a short period of time (seconds or minutes) are known as fast changes.burning of paper is fast change
2. Can deforestation be considered a desirable change? Explain.
- Undesirable change, The changes which are harmful to our environment.
3. What type of changes is associated with germination of a seed? Explain
- Ans: slow change,Changes which take place over a long period of time ( hours / days / months / years ) are known as Slow changes. Examples: growth of nail and hair, change of seasons, germination of seed
VIII. Answer in detail
1. Give one example in each case that happens around you.
- Slow and fast change
Slow:
Examples : growth of nail and hair, change of seasons, germination of seed
Fast:
Examples : Bursting of balloon, breaking of glass, bursting of fire crackers, burning of paper.
- Reversible and irreversible change
Reversible changes:
Examples: Touch me not plant (Responding to touch), stretching of rubber band, melting of ice.
Irreversible changes:
Examples : Change of milk into curd, digestion of food, making idly from batter
- Physical and chemical change
Physical changes:
Example : Melting of ice, the solution of salt or sugar, stretching of rubber band
Chemical changes:
Examples : Burning of wood, Popping of popcorn, Blackening of silver ornaments, and Rusting of iron
- d. Natural and man-made change
Natural changes:
Examples : Rotation of the earth, Changing phases of the Moon, Rain
Man-made changes:
Examples : Cooking, Deforestation, Cultivating crops, construction of building.
- e. Desirable and undesirable change
Desirable changes:
Examples : Ripening of fruit, growth of plants, cooking of food, milk changing to curd.
undesirable changes:
Examples : Deforestation, decaying of fruit, rusting of iron
