The answer to ur q's are as follows:
1# Why water boils quicker on mountains?
ANS:- This is becoz the atmospheric pressure on mountains is less and as a result the boiling temperature of water or temp. at wch water boils is reduced.....e.g. from 100 degrees centigrade to 97 or 98 degrees centigrade.
So it takes less time o reach this lower temp.
2# Why rainbow is produced in the sky after rainfall and sunlight?
ANS: This is due to the splitting of sunlight into it's 7 basic colours: VIBGYOR.....after sunlight passes thru a raindrop and is a result of refraction.
3# Why water remains cool in Earthenware pitcher?
ANS: This happens becoz when water evaporates from the surface of the pitcher a certain amount of energy or heat is required for evaporation or conversion of water droplets into water vapour so this heat is taken from the surface of the water in the pitcher and the water becomes cool.
4# Why milk is considered as an ideal food?
ANS: Milk contains many of the nutrients and vitamins that are required for the body although the body can not survive on milke alone.
5# Why meat takes longer to cook on the mountains?
ANS: As stated in answer to Q#1.....water boils at a lower temp. and a lower temp is reached by heating the cooking utensil so the meat only gets a lower temp. in wch it has to be cooked.....To solve this problem, the pressure cooker is used.....wch raises the tem of water above becoz of the increase in pressure on the water in the pressure cooker.
6# Why ice and salt mixture is used as a freezing agent in manual ice-cream maker?
ANS: This is becoz salt reduces the temp. of the ice and stops the ice from melting and maintains the temp. and thus keeps the ice-cream cold.
7# Why greenhouse operators paint their glass roof white in summer?
ANS: This is so that the white colour will reflect all the sunlight back and thus prevents the greenhouse from over-heating as white colour has the property of reflecting light and heat.
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