The exhaust of automobiles releases harmful gases which can affect the respiratory system drastically. Therefore, the policeman is wearing a mask to reduce the amount of pollutant intake.
Question
Why do you think, the policeman in the figure below is wearing a mask? 
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On a Sunday morning Paheli’s friend visited her home. She wanted to see some flowering plants in the nearby garden. Both of them went to the garden. While returning from the garden they also observed some flowering plants on the roadside. But to their surprise they found that the leaves and flowers of these roadside plants were comparatively very dull. Can you help them to know why?
Open Answer »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. i. Why did the tiny bubbles appear? ii. Do you think tiny bubbles will appear on heating the water taken out from the bottle? Justify your answer.
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