Class-5 EVS, Chapter-7 Experiments with Water, Additional exercises with Solutions


Chapter-7
Experiments with Water

Fill in the blanks with suitable words:
    1-    For making salt, water is allowed to dry in sun.
    2-    Dead Sea is the saltiest of all.
    3-    Common salt is soluble in water while chalk powder does not dissolve in water.
    4-    Iron nail sinks in water but the katori floats.

Match the column:
A
B
Oil and water
floats on sugarcane juice
Piece of ice
sinks in water
Empty plastic bottle
do not mix
Bottle full of water
floats on water

A
B
Oil and water
do not mix
Piece of ice
floats on sugarcane juice
Empty plastic bottle
floats on water
Bottle full of water
sinks in water

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Answer these questions
Q. A lemon sinks in a glass of plain water but floats on adding salt in the water. Why?
Ans.- A lemon sinks in a glass of plain water but floats on adding salt in the water because water becomes thicker (sense) on adding salt.

Q. Why does a person float in Dead sea, even after he does not know how to swim?
Ans.- A person floats in Dead sea, even after he does not know how to swim because Dead sea is the saltiest of all.
Q. Suggest some ways to quickly dissolve sugar in water for making shakkarpara.
Ans. Following are two ways to quickly dissolve sugar in water for making shakkarpara:
     1-    Stir the mixture of sugar and water thoroughly.
     2-    Warm the mixture over flame.

Q. Do you think that the oil gets dissolved in water? Why do you think so?
Ans.- No, the oil does not get dissolved in water. Oil always floats on water. This happens because water molecules are more attracted to each other than oil molecules.

Q. Why did Chittibabu and Chinnababu keep their mango jelly in the sun?
Ans- Chittibabu and Chinnababu keep their mango jelly in the sun so that water from jelly could be evaporated.

Q. Name some things that are made by drying in the sun at your house.
Ans. At my house following things are made by drying in the sun:
     1-    Potato chips
     2-    Papad
     3-    Amla candy
     4-    Moong badi
     5-    Sabudana papad

Q. How is the salt made?
Ans- The sea water is collected in shallow beds dug in sand. Water is allowed to dry in the sun. Salt remains on the ground after water is dried.

Q. You have washed your handkerchief and you want to dry it quickly. What all can you do?
Ans- We can do following things to dry our handkerchief quickly:
    1-    Squeeze water out.
    2-    Spread it in sun.
    3-    Dry with hot iron.

Q. What things do you put in water to make tea? Which of those things dissolved in water?
Ans- We put tea leaves, sugar in water to make tea. Sugar dissolves in water while only the extract of tea leaves comes into water. Rest of the tea is separated out.

Q. You have been given some mishri pieces (lumps of sugar). Suggest some ways to dissolve them quickly?
Ans-  Some ways to dissolve mishri quickly in water are as follows:
1-    Crush mishri pieces into fine powder.
2-    Stir water continuously
3-    Warm the water on flame.

Activity based questions:
Q. Take five different glasses of water and dissolve salt, soil, chalk powder, one spoon of milk and oil respectively in them. Record your observations in the table below:
Things
Did it dissolve in water or not
What happened after keeping for two minutes
Salt
Yes
Salt and water get mixed together completely. Water becomes transparent
Soil
No
Soil settles down at the bottom. Water looks muddy.
Chalk powder
No
Chalk powder settles down at the bottom.
A spoon milk
No
Milk and water get mixed and water becomes milky.
oil
No
Oil floats on the surface of water.


Q. Ayesha put two drops of oil and water each on her tiffin box. She tilted the lid and saw the drops racing down. Try to do the same experiment and tell- which drop went ahead? Why did it slide faster.
Ans- Water drop goes ahead of oil drop. This is because water is thinner than oil.
(More such activities given in text book should be performed in class)

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