Chhattisgarh State Board Class 6 Science Chapter 5 Changes Around Us Exercise Multiple Choice, Fill in the Blanks, Questions and Answers here.
Chhattisgarh State Class 6 Science Chapter 5 Solution
(1) Classify the following changes as slow or fast, reversible or irreversible, desirable or undesirable, cyclic or acyclic, physical or chemical changes –
1.) Formation of phases of moon – Cyclic change , Desirable change , Reversible change
2.) Lightening in the sky – Fast change , Undesirable change , Acyclic change
3.) Formation of natural gas from cow dung – Chemical change , Slow change , Irreversible change
4.) Combustion of petrol in a vehicle – Chemical change , Fast change , Irreversible change
5.) Formation of curd from milk – Physical change , Slow change , Irreversible change
(2) Fill in the blanks with the words physical or chemical –
1.) Digestion of food is a ( Physical ) change .
2.) Formation of water from ice is a ( Physical ) change .
3.) Curdling of milk is a ( Physical ) change .
4.) Melting of wax of a candle is a ( Physical ) change whereas its burning is a ( Chemical ) change .
(3) Match items in Column A with appropriate item in Column B
Column A Column B
Occurrence of earthquake – Non periodic change
Sprouting of seeds – Slow change
Melting of wax – Physical change
Occurrence of day and night – Periodic change
Bursting of crackers – Chemical change
(4) Answer the following questions –
1.) Explain whether the melting of ‘kulfi’ is a physical change or a chemical change
Melting of ‘ kulfi ‘ is a physical change because in melting of kulfi there is changes in physical properties
like shape and state . Also no new substance is formed .
2.) Write with reasons what kind of a change evaporation of water is.
Evaporation of water is a physical change . Because in evaporation water absorbs heat and changes its state
from liquid to gas but no new substance is formed .
4.) How is Pasteurisation done? What are the benefits?
To prevent spoiling of milk the pasteurisation method is used. In this method the milk is heated to a high and a desired temperature and then cooled immediately .
The benefit of this method are , in this method the microbes that spoil the milk die and the milk is pasteurised .
We can prevent the spoiling of milk by this method .
5.) State with examples how the same changes under different situations can be desirable or undesirable
In case of manufacturing plastic items , it can be desirable for its light weight and usefulness but in other point of view it can be undesirable because plastic is not bio degradable . this example shows how the same changes under different situations can be desirable or undesirable .
6.) State with examples the role of energy in bringing about changes
Energy is utilised during change . For example , in formation of water from ice and ice from water heat is absorbed and released respectively . In formation of Nitric oxide heat is absorbed and if water is poured on lime stone heat is released .
Hence in all physical and chemical changes either heat is released or absorbed .
7.) What is the kind of change that occurs during leaf fall in autumn? Explain.
A desirable change occurs during leaf fall in autumn . Because leaf fall in autumn is a natural change , for this change leaf falls and new leaf is grown which is useful for plants and us too .
(5) Write down the reasons for the following –
1.) Cooked food is kept in the refrigerator – to keep the food cold as in low temperature food stay fresh and it aslo protect food from spoiling .
2.) Salt is kept in an airtight box during rainy season – to stop the salt from absorbing moisture from the air and becomes wet .
3.) Ripening of guava is a chemical change – as the colour of guava is changed during ripening and ripened guava can not be change into fresh guava again .
4.) A coat of tin is put on iron sheets before making a box – to protect iron from getting rust .
5.) Rotation of fan is a cyclic change – as during the rotation the wings of fan moves at same speed and each wings come back to a initial position at a fixed time interval .
