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Solution:
A steel plate would float on water as it is lighter than water. On the other hand, a spoon which is heavier than water would sink. The size of a body does not decide whether it floats or sinks. It is the mass and volume of the body that collectively decide whether it floats or sinks.
The cap of a plastic bottle would float on water as it is lighter than water.
Do this experiment in groups of four friends. Each group will need a big pot filled with water and the things listed in the table. Put each thing one-by-one in water and observe.
Mark [√] for the things that float. Mark [×] for those that sink.
Things to be put in water | I guessed, before I did it | I saw, when I did it |
(a) Empty bowl (katori) (b) After putting in 6-7 small pebbles, one-by-one |
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Iron nail or pin | ||
Matchstick | ||
(a) Empty plastic bottle with its lid closed (b) Bottle half-filled with water (c) Bottle full of water |
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Aluminium foil (from medicine packing) (a) Open and spread out (b) Pressed tightly into a ball (c) In a cup-like shape |
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(a) Soap cake (b) Soap cake on a small plastic plate |
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A piece of ice |
Find out from the other groups which things floated and which sank in the water?
After doing the experiment, fill in the blanks.
Solution:
(i) the weight of water displaced by the iron nail is less than its own weight
(ii) the weight of water displaced by the katori is equal to its own weight.
(i) the weight of water displaced by the empty plastic bottle is equal to its own weight.
(ii) the weight of water displaced by the bottle filled with water is less than its own weight
(i) the weight of water displaced by the aluminium foil is equal to its own weight .
(ii) the weight of water displaced by the aluminium ball is less than its own weight
Solution:
When salt is added to water, the water gets heavy. As compared to a lemon, the salty water is heavier. So, the lemon that is lighter floats on salt water that is heavier.
Make groups of four friends. For the experiment you will need 4-5 glasses or bowls, spoons, water, and the things listed in the table. Take some water in each glass. Now try to dissolve one thing in one glass. Observe what happens and note in the table.
Things |
Did it dissolve or not? |
What happened after keeping for 2 minutes? |
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Solution:
Disclaimer: The purpose of this question is to introduce the children to the method of general science activities. This involves certain prior imagination followed by experimentation and logical deductions. Keeping this process of imagination and experimentation in mind, the answer to this question has not been provided.
Solution:
This is because as soon as salt is added into water it starts breaking down into smaller particles that are difficult to be seen by naked eyes. These salt particles get inside the water. At this stage, the salt starts dissolving in the water and a stage comes when the entire salt gets dissolved. Thus, no more salt could be seen.
The salt got broken into smaller particles that occupy the position in between the particles of water.
Out of the two substances, we would be able to separate chalk powder from water by straining with a cloth. This is because salt particles cannot be seen in water whereas chalk powder can be.
Disclaimer: The second part of the question aims to increase the process of scientific thinking in the students. Keeping this process of participation in mind, the answer to this question has not been provided.
One day Ayesha’s mother put some water to boil on the stove for making tea. She got busy with something and forgot about it. When she remembered and came back to check, she found only a few drops of water left in the pan.
Solution:
Chittibabu and Chinnababu kept their mango jelly under the sun in order to dry it.
Disclaimer: This question aims to make the students familiar with the things they come across in their daily lives. Keeping this process in mind, the answer to this question has not been provided.
Solution:
The ingredients used to make tea are water, tea leaves, milk and sugar. Among these, milk and sugar dissolve in water.
Some ways in which the mishri pieces can be dissolves quickly are
crush them and then dissolve them by stirring continuously
heat the water while continuously stirring in the pieces of mishri
Disclaimer: This question aims to make the students familiar with the things they come across in their daily lives. Keeping this process in mind, a sample answer has been provided and the answers of the students can vary from this answer.