10. How is salt made from sea water?
a) By boiling it
b) By filtering it
c) By letting it dry in the sun
d) By freezing it
(Answer: c By letting it dry in the sun)
True or False Questions
1. A wooden boat floats on water because it is lighter than a needle. (False)
2. An iron ship can float on water. (True)
3. An empty plastic bottle sinks in water. (False)
4. Adding salt to water can make things float that normally sink. (True)
5. Oil completely dissolves in water when stirred well. (False)
6. After salt dissolves in water, it completely disappears and is no longer present. (False)
7. Chalk powder dissolves in water just like salt does. (False)
8. In racing drops experiment, all drops slide down at the same speed. (False)
9. Water disappears when heated because it evaporates. (True)
10. The British had put a heavy tax on salt before India’s independence. (True)
Class 5 EVS Chapter 7 Experiments with water Questions and Answers
Q: Why does a puri float in oil when it puffs up?
A: When a puri puffs up, air fills inside it. Air is lighter than oil, so the puri floats.
Q: Why do some things float while others sink in water?
A: Things that are lighter than water for their size float. Things that are heavier than water for their size sink.
Q: What happens when you add lots of salt to water?
A: The water becomes very salty and heavy. Things like eggs and lemons that usually sink can float in very salty water.
Q: Why can’t we see salt after it dissolves in water?
A: When salt dissolves, it breaks into very tiny pieces that are too small to see. But the salt is still there in the water.
Q: What’s the difference between how salt and chalk powder behave in water?
A: Salt dissolves completely and disappears. Chalk powder does not dissolve completely some of it sinks to the bottom.
Q: Why do oil and water not mix properly?
A: Oil and water don’t mix because they are different types of liquids. Oil stays as small drops in the water.
Q: In the racing drops experiment, why did some drops slide faster?
A: Some liquids are thinner and flow more easily, so they slide faster. Thicker liquids move more slowly.
Q: Where does water go when it is heated in a pan?
A: When water is heated, it turns into steam (water vapor) and goes into the air. This is called evaporation.
Q: Why did Gandhiji go on the Dandi March?
A: Gandhiji went on the Dandi March to protest against the British law that didn’t allow Indians to make their own salt and forced them to pay high taxes on salt.
Q: How is salt made from sea water?
A: Salt is made by collecting sea water in shallow beds in the sand and letting the water dry in the sun. After the water dries, salt remains on the ground.
