Physical And Chemical Changes Worksheet

           Objective Type Questions

1. Select the odd one out and give reason for the same.
   (a)Cake baking
   (b)Digestion of food
   (c)Wood cutting
   (d)Candle burning
   
   
2. Match the terms in column A with appropriate terms in column B.
   
   
   
3. State whether the following statements are true or false. In case of false statement, write the correct one.
   (i)Photosynthesis is a physical change.
   
   (ii)Tearing of paper is an irreversible process, hence it is a chemical change.
   
   
   Multiple Choice Questions
   
   
4. Renu bought few iron nails for the house renovation. Few of those were used for window hanging while other were drilled in wall for hanging murals. Which of them would get rust easily?
   
   (a) Window
   (b) Wall
   (c) Both of above
   (d) None of above
   
   
5. Doctor explained Abhishek how eating an egg daily would help him to recover from protein deficiency. Breakdown of food into simpler substances is:
   
   (a) a physical change
   (b) a chemical change
   (c) physical as well as chemical change
   (d) None of the above
   
   
6. Kiran burnt tip of a magnesium ribbon. It burnt with a bright white flame and some gases before it turned to ashes.
   
   (i) Magnesium melts, get vapourised and again solidifies into ash.
   (ii) Magnesium changes its colour and appearance to form ash
   (iii) Magnesium metal reacts with oxygen in air to form new substance.
   Which of the above statements about this process is/are correct?
   (a) Only (i)
   (b) (ii) and (iii)
   (c) Only (iii)
   (d) All of three
   
   
7. Sunil’s uncle gifted him a box full of mangoes while leaving from native and told him to keep a check on them daily and finish.  Next day, Sunil saw that fresh mangoes had ripened, and two of the ripe mangoes had rotted. What kind of change occurred within the fresh mangoes?
   
   (a) Physical change as the appearance of mangoes changed
   (b) Chemical change as the smell of mango changed.
   (c) Physical change as the colour of mangoes changed.
   (d) Chemical change as ripening process cannot be reversed.
   
   
8. Rita dipped an iron nail in copper sulphate solution then after some time, the colour of the solution changes from blue to pale green and iron nail gets covered by red coloured deposit. Change of the colour can indicate both, a chemical as well as a physical change.
   What type of change does this experiment signify?
   
   (i) Chemical change because of red coloured deposit on iron nail
   (ii) Physical change because colour of the solution changes
   (a) Only (i) 
   (b) Only (ii)
   (c) Both (i) and (ii)
   (d) None of the above
   
   
9. Prachi mixes flour, milk, eggs and water to create a batter for baking cake. The steps in the process are:
   Step 1: Mix flour, water, eggs, sugar and milk in a bowl.
   Step 2: Place the batter in a baking tray
   Step 3: Bake in the oven.
   Which of the following is the correct option?
   (a)Step 1: Physical change, Step 2: Chemical change, Step 3: Chemical change
   (b)Step 1: Physical change. Step 2: Physical change, Step 3: Chemical change
   (c)Step 1: Chemical change, Step 2: Physical change, Step 3: Physical change
   (d)Step 1: Chemical change, Step 2: Physical change,  Step 3: Chemical change
   
   Subjective Questions
   
   
10. Justify: Candle burning is physical as well as chemical change.
    
    
11. Teacher asked Sheetal, Rashmi and Arun to prepare pure crystals of copper sulphate from its solution. All three of them procured the required material and followed the steps as shown below:
    
    Whose flask would the first crystals of copper sulphate appear in and why?
    (a)Sheetal
    (b)Rashmi
    (c)Arun
    (d)All of three
    
    
12. Distinguish between physical and chemical properties?
    
    
13. Classify below events into physical and chemical changes.
    (a) Formation of clouds
    (b) Melted wax vapourisation
    (c) Combustion of petrol
    (d) Stretching of rubber band
    (e) Curdling of milk
    
    
14. Ridhan left out a block of ice cream, 4 cm in length, in a bowl for some time. It melted into liquid. He then kept the bowl in the freezer. Now, the ice cream formed has the diameter of the bowl. What kind of change occurs in the ice cream and why?
    
    
15. Akshata added a bit of baking soda to vinegar in a test-tube. She heard a hissing sound and saw several bubbles in the test tube. She closed the test tube with a cork that is attached to another test tube containing lime water by a glass tubing. The limewater slowly turns milky in the process. This is shown in the following experimental setup.
    
    Below mentioned are the observations:
    (a) Hearing of a hissing sound
    (b) Bubbles formation in test tube A
    (c) Gas movement through glass tubing
    (d) Change of the colour in test tube B
    Categorise these observations into physical changes and chemical changes.
    
    Case-Based Questions
    
    
16. Read the passage and answer the following questions (a), (b) and (c):
    It is known that ships are made of iron, and a part of them is submerged under water. Also, water drops cling to the ship's outer surface above water. Additionally, sea water contains many salts. As a result of the salt water, rust forms more quickly. Despite being painted, ships suffer a lot from rusting.
    
    (a) Express rusting in the form of an equation.
    (b) Which essential environmental elements assist rusting?
    (c) Suggest any two ways to prevent rusting.
    
    
17. Read the passage and answer the following questions (a), (b) and (c):
    In Class VI you have learnt that salt can be obtained by the evaporation of sea water. The salt obtained in this manner is not pure and the shape of its crystals cannot be seen clearly. However, large crystals of pure substances can be formed from their solutions.
    
    (a) Define crystallisation.
    (b) Select which of the following substances when kept overnight can be recovered from water without any loss? If ‘Yes’, then how and if ‘No’ then why?
    (i) Common salt dissolved in water
    (ii) Iron nail kept in water
    (iii) Sugar dissolved in water
    (iv) Copper plate kept in water
    (c) Give two applications of crystallisation.
    
    Assertion-Reasoning Questions
    
    Below questions consist of two statements – Assertion (A) and Reason (R). Answer these questions selecting the appropriate option given below: 
    
18. Assertion (A): Breaking of a glass is a physical change.
    Reason (R): Breaking is an irreversible change.
    
    
19. Assertion (A): Candle burning is a physical change.
    Reason (R): Change in the physical properties such as size, shape, state is termed as physical change.
    
    
20. Assertion (A): Ozone protects us from harmful UV rays coming from the Sun.
    Reason (R): Oxygen reacts with UV rays to form ozone molecule.

            Objective Type Questions

1. Select the odd one out and give reason for the same.
   (a)Cake baking
   (b)Digestion of food
   (c)Wood cutting
   (d)Candle burning
   Correct option: (c) Wood cutting
   Solution: Cut parts of wood retains the chemical characteristics of original wood block,
   Cake baking, digestion of food and candle burning are chemical changes.
   
   
2. Match the terms in column A with appropriate terms in column B.
   
   Solution:
   
   
   
3. State whether the following statements are true or false. In case of false statement, write the correct one.
   (i)Photosynthesis is a physical change.
   
   (ii)Tearing of paper is an irreversible process, hence it is a chemical change.
   
   (i) Correct option: (b) False.
   Solution: In photosynthesis, carbon dioxide and water react with each other in presence of chlorophyll and Sunlight to form sugar and oxygen. Hence, it is a chemical change.
   
   (ii) Correct option: (b) False
   Solution: Though tearing of paper is irreversible, but the torn paper has the same chemical properties as that of original untorn paper.
   
   Multiple Choice Questions
   
   
4. Renu bought few iron nails for the house renovation. Few of those were used for window hanging while other were drilled in wall for hanging murals. Which of them would get rust easily?
   
   (a) Window
   (b) Wall
   (c) Both of above
   (d) None of above
   Correct option: (a) Window
   Solution: For rusting, two essential elements are water and oxygen. Iron nails used for window have constant exposure to atmospheric moisture and oxygen along with outside heat which enhances further the rusting process.
    
5. Doctor explained Abhishek how eating an egg daily would help him to recover from protein deficiency. Breakdown of food into simpler substances is:
   
   (a) a physical change
   (b) a chemical change
   (c) physical as well as chemical change
   (d) None of the above
   Correct option: (b) a chemical change
   Solution: Digestion of food is a chemical change since, food particles get broken down into simpler substances in the presence of gastric juices.
   
   
6. Kiran burnt tip of a magnesium ribbon. It burnt with a bright white flame and some gases before it turned to ashes.
   (i) Magnesium melts, get vapourised and again solidifies into ash.
   (ii) Magnesium changes its colour and appearance to form ash
   (iii) Magnesium metal reacts with oxygen in air to form new substance.
   Which of the above statements about this process is/are correct?
   (a) Only (i)
   (b) (ii) and (iii)
   (c) Only (iii)
   (d) All of three
   Correct option:  (b) (ii) and (iii)
   Solution:
   Evolution of gases result from the reaction between magnesium and oxygen present in the air.
   Magnesium metal reacts with oxygen present in the air to form new substance magnesium oxide.
   
   
7. Sunil’s uncle gifted him a box full of mangoes while leaving from native and told him to keep a check on them daily and finish.  Next day, Sunil saw that fresh mangoes had ripened, and two of the ripe mangoes had rotted. What kind of change occurred within the fresh mangoes?
   
   (a) Physical change as the appearance of mangoes changed
   (b) Chemical change as the smell of mango changed.
   (c) Physical change as the colour of mangoes changed.
   (d) Chemical change as ripening process cannot be reversed.
   Correct option: (d) Chemical change as ripening process cannot be reversed.
   Solution: Ripening process results into new substances due to chemical change which cannot be reversed.
   
   
8. Rita dipped an iron nail in copper sulphate solution then after some time, the colour of the solution changes from blue to pale green and iron nail gets covered by red coloured deposit. Change of the colour can indicate both, a chemical as well as a physical change.
   What type of change does this experiment signify?
   (i) Chemical change because of red coloured deposit on iron nail
   (ii) Physical change because colour of the solution changes
   (a) Only (i)
   (b) Only (ii)
   (c) Both (i) and (ii)
   (d) None of the above
   Correct option: (a) Chemical change because of red coloured deposit on iron nail.
   Solution: The red coloured deposit is the new substance i.e. copper metal formed by the chemical reaction between copper sulphate and iron.
   
   
9. Prachi mixes flour, milk, eggs and water to create a batter for baking cake. The steps in the process are:
   Step 1: Mix flour, water, eggs, sugar and milk in a bowl.
   Step 2: Place the batter in a baking tray
   Step 3: Bake in the oven.
   Which of the following is the correct option?
   (a) Step 1: Physical change, Step 2: Chemical change, Step 3: Chemical change
   (b) Step 1: Physical change. Step 2: Physical change, Step 3: Chemical change
   (c) Step 1: Chemical change, Step 2: Physical change, Step 3: Physical change
   (d) Step 1: Chemical change, Step 2: Physical change,  Step 3: Chemical change
   Correct option: (d) Step 1: Chemical change, Step 2: Physical change,  Step 3: Chemical change
   Solution: In step 1, while mixing flour, water, eggs, sugar and milk in a bowl, their particles start reacting with each other. Placing the batter made in step 1 in baking tray will change the shape which is physical property. Step 3 is chemical change because, baking of batter results into chemical reaction along with evolution of gas to make the cake spongy.
   
   Subjective Questions
   
   
10. Justify: Candle burning is physical as well as chemical change.
    Solution:
    Candle burning is a physical as well as a chemical change. The physical change occurs when the wax melts and loses its shape. The chemical change is the combustion of fuel in presence of oxygen. This leads to the production and emission of carbon dioxide from the flame.
    
    
11. Teacher asked Sheetal, Rashmi and Arun to prepare pure crystals of copper sulphate from its solution. All three of them procured the required material and followed the steps as shown below:
    Whose flask would the first crystals of copper sulphate appear in and why?
    (a)Sheetal
    (b)Rashmi
    (c)Arun
    (d)All of three
    Solution:
    The correct option is (c) Arun. This is because, Arun cooled the salt solution in ice-cold water, which enhances the crystallisation process. Sheetal and Rashmi also cooled the salt solution, but at room –temperature, so the crystallisation process would be lengthier.
12. Distinguish between physical and chemical properties?
    Solution:
    
    
    
13. Classify below events into physical and chemical changes.
    (a) Formation of clouds
    (b) Melted wax vapourisation
    (c) Combustion of petrol
    (d) Stretching of rubber band
    (e) Curdling of milk
    Solution:
    
    
    
14. Ridhan left out a block of ice cream, 4 cm in length, in a bowl for some time. It melted into liquid. He then kept the bowl in the freezer. Now, the ice cream formed has the diameter of the bowl. What kind of change occurs in the ice cream and why?
    Solution:
    The ice cream got melted in the bowl and was again frozen in the same bowl which gave it bowl’s shape. Thus, there is a change only in physical property and not in a chemical property. Hence, it is a physical change.
    
    
15. Akshata added a bit of baking soda to vinegar in a test-tube. She heard a hissing sound and saw several bubbles in the test tube. She closed the test tube with a cork that is attached to another test tube containing lime water by a glass tubing. The limewater slowly turns milky in the process. This is shown in the following experimental setup.
    Below mentioned are the observations:
    (a) Hearing of a hissing sound
    (b) Bubbles formation in test tube A
    (c) Gas movement through glass tubing
    (d) Change of the colour in test tube B
    Categorise these observations into physical changes and chemical changes.
    Solution:
    
    
    Case-Based Questions
    
    
16. Read the passage and answer the following questions (a), (b) and (c):
    It is known that ships are made of iron, and a part of them is submerged under water. Also, water drops cling to the ship's outer surface above water. Additionally, sea water contains many salts. As a result of the salt water, rust forms more quickly. Despite being painted, ships suffer a lot from rusting.
    
    (a) Express rusting in the form of an equation.
    (b) Which essential environmental elements assist rusting?
    (c) Suggest any two ways to prevent rusting.
    Solution:
    (a)Rusting is represented by the following equation:
       Iron (Fe) + Oxygen (O₂, from the air) + water (H₂O) → rust (iron oxide Fe₂O₃)
    (b)Essential environmental elements which assist rusting are oxygen and water (or water vapour).
    (c)It is possible to prevent rusting by painting iron metal or galvanizing iron, which involves coating it with zinc.
    
    
17. Read the passage and answer the following questions (a), (b) and (c):
    In Class VI you have learnt that salt can be obtained by the evaporation of sea water. The salt obtained in this manner is not pure and the shape of its crystals cannot be seen clearly. However, large crystals of pure substances can be formed from their solutions.
    
    (a) Define crystallisation.
    (b) Select which of the following substances when kept overnight can be recovered from water without any loss? If ‘Yes’, then how and if ‘No’ then why?
    (i) Common salt dissolved in water
    (ii) Iron nail kept in water
    (iii) Sugar dissolved in water
    (iv) Copper plate kept in water
    (c) Give two applications of crystallisation.
    Solution:
    The process of obtaining large crystals of a salt from its salt solution by either evaporation or cooling is called crystallisation.
    (b) The substances which can be recovered from water without any loss are:
    (i) Common salt dissolved in water
    (iii) Sugar dissolved in water
    Common salt and sugar can be recovered from water by crystallisation process.
    The substances which can be recovered from water but with loss are:
    (ii) Iron nail kept in water
    (iv) Copper plate kept in water
    Some of the metal will get corroded in water. In case of iron, it is called rusting.
    (c) Applications of crystallisation:
    Separation of salt from sea water. Purification of alum from impure alum.
    
    Assertion-Reasoning Questions
    
    Below questions consist of two statements – Assertion (A) and Reason (R). Answer these questions selecting the appropriate option given below: 
18. Assertion (A): Breaking of a glass is a physical change.
    Reason (R): Breaking is an irreversible change.
    Correct option: (b) Both A and R are true but R is not the correct explanation of A
    Solution: Reason statement can be, “Though breaking of glass is an irreversible change, the chemical properties of broken glass remains unchanged.”
    
    
19. Assertion (A): Candle burning is a physical change.
    Reason (R): Change in the physical properties such as size, shape, state is termed as physical change.
    Correct option: (d) A is false but R is true.
    Solution: Candle burning is physical as well as chemical change wherein melting of wax is a physical change while combustion of wax and wick is a chemical change.
    
    
20. Assertion (A): Ozone protects us from harmful UV rays coming from the Sun.
    Reason (R): Oxygen reacts with UV rays to form ozone molecule.
    Correct answer: (c) A is true but R is false.
    Solution: Assertion statement is true.
    Reason: Ozone absorbs this UV radiation and breaks down to oxygen.