Paheli kept some water in a beaker for heating. She observed that tiny bubbles appeared before the water started to boil. She boiled the water for about 5 minutes and filled it in a bottle up to the brim and kept the bottle airtight till it cooled down to room temperature.

(a) Why did the tiny bubbles appeared?

(b) Do you think tiny bubbles will appear on heating the water taken out from the bottle? Justify your answer

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Solution

(a)
Water has dissolved air in it. When Paheli boils the water, air rises up and escapes out in the form of bubbles.
(b)
When Paheli boiled the water for the first time, all air escaped out. So, on heating the same water after cooling, tiny bubbles would not appear.

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(a) Water has dissolved air in it. When Paheli boils the water, air rises up and escapes out in the form of bubbles.​ (b) When Paheli boiled the water for the first time, all air escaped out. So, on heating the same water after cooling, tiny bubbles would not appear.​

(a)
Water has dissolved air in it. When Paheli boils the water, air rises up and escapes out in the form of bubbles.
(b)
When Paheli boiled the water for the first time, all air escaped out. So, on heating the same water after cooling, tiny bubbles would not appear.