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.
(a) The tiny bubbles appeared before the water started to boil since the air dissolved in water. Once the water started to boil, the air dissolved in water escaped in the form of bubbles.
(b) Paheli had boiled the water completely where the air from the water had escaped out, so reheating the cooled boiled water will not make any tiny bubbles as there is no air present in it.
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Take out a cooled bottle of water from refrigerator and keep it on a table. After some time you notice a puddle of water around it. Why?
Keep a chilled bottle from the fridge on normal room temperature, you will find some droplets of water on it. Give a reason for these droplets.
During summer, Boojho carries water in a transparent plastic bottle to his school. One day he left his bottle in the school. The bottle still had some water left in it. The following day, he observed some water droplets on the inner surface of the empty portion of the bottle. These droplets of water were formed due to(a) boiling and condensation(b) evaporation and saturation(c) evaporation and condensation(d) condensation and saturation
Why a bottle filled with water makes a sound?
Boojho took an empty plastic bottle, turned it upside down and dipped its open mouth into a bucket filled with water. He then tilted the bottle slightly and made the following observations.Bubbles of air came out from the bottle.Some water entered the bottle.Nitrogen gas came out in the form of bubbles and oxygen got dissolved in water.No bubbles formed, only water entered the bottle.Which observations is / are correct?(a) (i) and (ii)(b) (iv) only(c) (iii) and (iv)(d) (i) only
Paheli kept an empty bottle made of plastic inside a refrigerator. After few hours, when she opened the refrigerator she found the bottle had collapsed. Explain the possible reason.
Prasanna wanted to buy deodorant from the shop. While buying a bottle, he felt that it was slightly heavier than the usual deodorant bottle that he purchased every time. He read the weight mentioned on the bottle and told the shopkeeper to weigh the same. He found the bottle was heavy, and on opening the deodorant bottle, he found it half-filled with water. He complained about the matter to the consumer authority.(a) Define density.(b) Apart from water, what is the other substance that some shopkeepers add to the deodorant?(c) What value of Prasanna is reflected in this act?
In which of the following case evaporation of water will be the slowest?(a) A tray of water kept in sunlight.(b) A kettle of water kept on a burner.(c) A glass of water kept in a room.(d) A bucket of water kept on rooftop.
Why We See More Bubbles In Cathode Beaker Than Anode Beaker During The Electrolysis Of Acidified Water?
Vidya and Pratap went for a picnic. Their mother gave them a water bottle that contained 5 litres of water. Vidya consumed $\frac{2}{5}$ of the water. Pratap consumed the remaining water.1. How much water did Vidya drink?2. What fraction of the total quantity of water did Pratap drink?
Name the process associated with the following(a) Dry ice is kept at room temperature and at one atmospheric pressure.(b) A drop of ink placed on the surface of water contained in a glass spreads throughout the water.(c) A potassium permanganate crystal is in a beaker and water is poured into the beaker with stirring.(d) An acetone bottle is left open and the bottle becomes empty.(e) Milk is churned to separate cream from it.(f) Settling of sand when a mixture of sand and water is left undisturbed for some time.(g) Fine beam of light entering through a small hole in a dark room, illuminates the particles in its paths.
If we put an empty closed plastic bottle in water, it floats but same filled with sand, sinks in water. Why?
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