Give reasons :
Why is mercury preferred over water in making thermometers even though both of them have similar coefficient of volume expansion ?

Give reasons : Why is alcohol used instead of mercury in thermometers these days ?

Give reasons Why are reflecting telescopes preferred over refracting telescopes?

Give reasons : Why does your mother put folded cloth strips soaked in cold water on your forehead when you have high fever ?

Apparatus: Two aluminium tins of the same size, two small galsses, water, thermometers, black paint, etc. : Procedure: Paint the outer surface of one tin black paint, and let it dry. Then in both tins, place one glass, each filled with water at the same temperature. cover the tins with lids. Keep them in the sun for two hours. Now measure the temperature of the water in the glasses in the two tins. What is the reason for the difference in the temperature?

Give scientific reasons: Even though a heat is supplied to boiling water, there is no increase in its temperature.

Give scientific reasons: If we bring an object closer than 25 cm from the eyes, why can we not see it clearly even though it subtends a bigger angle at the eye?

Take three similar vessels . Let us call them A,B and C ( see figure below ) Fill A with hot water and B with cold water . Put some water from A and B in C . Dip you right hand in A and left hand in B , and keep them immersed for 2 to 3 minutes . Now dip both the hands in C .: What is the reason for this ? think about it .: