General Science
5th Class
Chapter 5
Physical and Chemical Changes of Matter
Questions
1. Encircle the correct option.
i. The change of milk into yogurt is:
a. Physical change b. Climate change
c. Chemical change d. Change of colour
ii. Why did a person paint his iron gate?
a. To save from rusting b. To save from sunlight
c. To make it beautiful d. To save from water
Out of these which answer is correct?
a. 1 and 2 b. 1 and 3 c. 2 and 3 d. 1 and 4
iii. Which factor will not affect the dissolving of sugar in water?
a. Adding salt in water b. Making sugar powder by grinding
c. Heating water and sugar d. Stirring water and sugar
iv. Which one is not a chemical change?
a. Seed germination b. Making paper boat
c. Burning of wood d. Cooking food
v. What type of change is it when metal expands on heating?
a. Permanent b. Chemical c. Physical d. Temporary
2. Write short answers.
i. Explain evaporation giving examples from everyday life.
Ans.
The change of water into water vapours is called evaporation. From wet surfaces, water continuously moves in to the surrounding air, this process occurs continuously from the surfaces of canals, lakes, rivers and oceans etc. This process also takes place from the snow surface and from the leaves of plants.
ii. Define condensation.
Ans.
The change of water vapours in to liquid and stick with the external surface of glass is called condensation.
iii. What is rusting and which type of change is this?
Ans.
The change that occurred on the iron due to the action of oxygen and water is called rusting. This is a permanent chemical change.
Iron + Oxygen + Water = Rusting
iv. Give an example of chemical change in which carbon dioxide is produced?
Ans.
When slaked lime is added in water it produces carbon dioxide.
v. Explain the three states of matter and their interconversion.
Ans.
Solid is the state in which matter maintains a fixed volume and shape. Liquid takes the shape of its container. Gas spreads out to fill any container. All the three states of matter are changed in one another on heating for example ice (solid) changes into liquid (water), and liquid (water) changes into gas (steam).
3. Constructed Response Questions:
i. Weigh one fourth of a glass of vinegar and tea spoon of baking soda. Then mix them together. As a result, bubbles will be formed. Weigh this compound again. Now its weigh will become less than the previous one. How will you explain the loss of the weigh?
Ans. There is a chemical reaction occur due to which gas is released in the form of bubbles due to this, there is loss of weight.
ii. On mixing vinegar and boiling water bubbles are produced. Out of the two one is chemical change and the other one is physical change. Explain.
Ans. On mixing vinegar there is chemical change, due to which bubbles of gas evolved, while boiling of water is a physical change.
iii. A student weighs a piece of ice and then allows it to melt. In your opinion what will be the weight of water and why?
Ans. The weight of water will decrease because some water evaporates from the surface.
4. Investigate:
i. Why is the formation of fertilizer from leaves is a chemical change?
Ans. The formation of fertilizer from leaves is a chemical process because once leaves is rotten to form it, they will never become reversed into their original condition.
5. Project:
Removal of Eggs Shell by Chemical Process.
Material Required:
- Egg
- Vinegar
- Vessel to keep eggs
i. Table an egg in a vessel or jar. Pour vinegar on it so that the egg is immersed into it. Bubbles will be formed on the egg's surface.
ii. Leave it for 12 hours. Carefully take out the egg from the vessel then was it gently and observe the egg.
iii. You will observe that the shell of the egg has disappeared.
iv. What have you come to know from this observation?
Ans: When egg is immersed in a jar on pouring the vinegar, the egg shell is dissolved due to chemical change.
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