CBSE Class 5 Subject EVS
NCERT Solutions
CHAPTER -7
EXPERIMENTS WITH WATER
NCERT Solutions
CHAPTER -7
EXPERIMENTS WITH WATER
1. Ayesha put a puffed puri in a bowl of water. Would it sink or float?
Ans. It would float.
2. You put a steel plate on water. Would it sink or float? What would happen to a spoon?
Ans. If the steel plate is put carefully over the surface of water, it would float. However, the spoon will sink.
3. Would the cap of plastic bottle cap sink or float on water?
Ans. It would float.
4. Have you seen that something float on water while of hers sink? Think how this happens!
Ans. Yes, I think that, when water displaced by any thing is greater than it weight, it floats on water otherwise it sinks.
5. Find out from the other groups which things float and which sank in the water?
Ans. A football, a piece of thermocol etc. float on water while a cricket ball, a spoon etc. sink.
After doing the experiment, write
1. The iron nail sank in the water but the katori floated. I think this happened because the weight of water displaced by the iron was less than it but the weight of water displaced by the katori was more than it.
2. The empty plastic bottle floated on water. The bottle filled with water sank because the weight of water displaced by the empty plastic bottle was more than its weight but the weight of bottle filled with water was more that that of the weight of watered displaced by it.
3. The aluminum foil floated when it was spread out. When pressed tightly into a ball it sank. This may have happened because the weight of aluminum foil is less than that of water displaced by it but the weight of aluminum ball is more than that of the water displaced by it.
6. Take some water in a glass. Put a lemon in it. Now keep putting salt in the water, half-a-spoon at a time. Were you able to float your lemon in water?
Ans. Yes, the lemon starts to float on water.
7. What do you think, the lemon floated in salty water because….
Ans. Because after adding salt, water because sticker.
8. Make groups of four friends. For the experiment you will need 4-5 glasses or bowls or bowls and the things listed in the table. Take some water in each glass. Now try to dissolve one thing in one glass. Observe that happens and note in the table.
Ans.
Things
|
Did it dissolve or not?
|
What happened after
Keeping for 2 minutes?
|
1. Salt
|
Yes
|
Salt and water got mix together completely.
|
2. Soil
|
No
|
Soil settled down at the bottom of the glass.
|
3. Chalk powder
|
No
|
Chalk settled down at the bottom of the glass.
|
4. 1 Spoon milk
|
Yes
|
Milk and water got mixed together completely.
|
5. Oil
|
Yes
|
Oil floats on the surface of water.
|
9. Could you see the salt after it dissolved in water? If no, why?
Ans. No, because salt got dissolved completely into the water.
10. Does that mean the water does not have salt? If it has, then where is the salt?
Ans. Of course, water contains salt. It is completely mixed up with water.
11. What difference did you see in water with salt and water with chalk powder after keeping for sometime?
Ans. Water and salt got mixed together completely while chalk powder settle down at the bottom of water.
12. Which of the two would you be able to separate from the water by straining with a cloth-salt or chalk powder?
Ans. We can separate chalk powder by straining with a cloth.
13. Do you think the oil dissolved in the water? Why do you think so?
Ans. I do not think so because oil is insoluble in water.
14. You also try to do the same and then which drop went ahead? Why did it slide faster?
Ans. The water drop went ahead. It happens because water does not stick to the tiffin box but the oil drop sticks.
15. One day Ayesha’s mother put some water to boil on the stove for making tea. She got busy with something and forget about it. When she remembered and came to check, she found only a few drops of water left in the pan.
Think where did the water go?
Ans. The water evaporated.
16. Why did Chittibabu and Chinnubabu keep their mango jelly in sun?
Ans. They did so to evaporated water from their mango jelly.
17. At your house, what things are made by drying in the sun?
Ans. Eatables like mango jelly (aam papad), papad, badis and potato chips are made by keeping in the sum.
18. You have washed you handkerchief and you want to dry it quickly. What all can you do?
Ans. For that, first the water from the handkerchief should be squeezed out properly and then it should be kept in the sun or pressed (by iron).
19. What things do you put in water to make tea? Which of these things dissolve in water?
Ans. To make tea, we add milk, tea leaves and sugar into the water. Out of these milk and sugar get dissolved.
20. You have been given some mishri pieces (lumps of sugar). Suggest some ways to dissolve them quickly.
Ans. To dissolve the mishri quickly. First it should be crushed to make powder of it. Then after adding it into water, the mixture should be stirred thoroughly.
The mixture could also be heated over the flame to dissolve the mishri quickly.
