Posts
VI SCIENCE CHANGES AROUND US EVALUATION QUESTION ANSWERS
CHANGES AROUND US
EVALUATION
I. Choose the appropriate answer
1. When ice melts to form water, change occurs in its
a. position
b. colour
c. state
d. Composition
Ans: c. state
2. Drying of wet clothes in air is an example of
a. Chemical change
b. Undesirable change
c. irreversible change
d. physical change
Ans: c. irreversible change
3. Formation of curd from milk is
a. a reversible change
b. a fast change
c. an irreversible change
d. an undesirable change
Ans: c. an irreversible change
4. Out of the following an example of a desirable change is
a. rusting
b. change of seasons
c. earthquake
d. Flooding
Ans: b. change of seasons
5. Air pollution leading to Acid rain is a
a. reversible change
b. fast change
c. natural change
d. human made change
Ans: d. human made change
II. Fill in the blanks
1. Magnet attracts iron needle. This is____________ change.
(a reversible / an irreversible)
Ans: a reversible
2. Boiling of egg results in_______________ change.
(a reversible / an irreversible)
Ans: an irreversible
3. Changes that are harmful to us are ___________ .
(desirable / undesirable)
Ans: undesirable
4. Plants convert Carbon-di-oxide and water into starch. This is an example of _________change. (natural / human made)
Ans: natural
5. Bursting of firecrackers is a __________change whereas germination of seeds is a _______change. (slow / fast)
Ans: fast, slow
III. True or False. If False, give the correct statement
1. Growing of teeth in an infant is slow change.
Ans: True
2. Burning of match sticks is a reversible change.
Ans: False
Burning of match sticks is an irreversible change.
3. Change of new moon to full moon is human-made.
Ans: False
Change of new moon to full moon is natural.
4. Digestion of food is a physical change.
Ans:False
Digestion of food is a chemical change.
5. In a solution of salt in water, water is the solute
Ans: False
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 change
2. Photosynthesis : __________ change :: burning of coal : Human – made change
Ans: natural
3. Dissolution 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: Blinking of eye.- fast change
All other changes are slow changes.
2. Glowing of a bulb, lighting of a Candle, breaking of a coffee mug, curdling of milk
Ans: curdling of milk - Slow change
All other changes are fast changes.
3. Rotting of an egg, condensation of water vapour, trimming of hair,
Ripening of fruit
Ans: Rotting of an egg - Undesirable change
All other changes are desirable changes.
4. Inflating a balloon, popping a balloon, fading of wall paint, burning of kerosene
Ans:Inflating a balloon - Reversible change
All other changes are irreversible changes.
VI. Give very short answer
1. What kind of a change is associated with decaying of a plants?
The change associated with decaying of plants is slow change.
2. You are given some candle wax. Can you make a candle doll from it? What kind of change is this?
Yes, I can make a candle doll from wax. It is a 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.
When sugar is heated, it loses water molecules and black powdery substance is formed. The substance is known as Charred sugar. This is a chemical and irreversible change.
5. What is a solution?
When solute is dissolved in a solvent it forms a solution.
Solute + Solvent → Solution
VII. Give short answer
1. What happen when paper is burnt? Explain.
✱Burning of paper takes place within a short period (seconds/ minutes) of time.
✱It is a fast , irreversible and chemical change.
2. Can deforestation be considered a desirable change? Explain.
✱No, deforestation can not be considered as a desirable change.
✱It leads to changes like global warming and decrease of rainfall etc.
✱The changes which are harmful to our environment and not desired by us are known as undesirable changes.
3. What type of changes is associated with germination of a seed? Explain
✱Germination of a seed is a slow change.
✱Changes which take place over a long period of time ( hours / days / months / years ) are known as slow changes.
VIII. Answer in detail
1. Give one example for each case that happens around you.
a. Slow and fast change
b. Reversible and irreversible change
c. Physical and chemical change
d. Natural and man-made change
e. Desirable and undesirable change
IX. Question based on Higher Order Thinking Skills.
1. When a candle is lit the following changes are observed.
a. Wax melts.
b. Candle keeps burning.
c. The size of the candle decreases.
d. The molten wax solidifies
e. Which of the changes can be reversed? Justify your answer.
a. Wax melts - Reversible change
Only the state of wax changes from solid to liquid. It is a reversible change.
b. Candle keeps burning - Chemical change
When a candle is burned, chemical reactions take place between the wax and oxygen and releases energy in the form of heat and light.
c. The size of the candle decreases - Irreversible change
The size of candle reduces and cannot be brought back into its original size (during burning)
d. The molten wax solidifies - Reversible change
We can make a new shape of wax from the solidified form of wax.
