Q: Why does not the electric filament in an electric bulb burn up?
Ans:- the electric filament in an electric bulb burn up due to the two reasons that is high melting point of tungsten and absence of oxygen.
Firstly, because it is made of tungsten which has a very high melting point (34100) whereas the temperature of the filament required to glow is only 27000 C . Secondly, oxygen is absent since the bulb is filled with an inert gas which does not help in burning.
Q:- Why does blotting paper absorb ink?
Ans:- This is due to the capillary action of the blotting paper. Blotting paper has fine pores which act like capillaries. When a portion of blotting paper is brought in contact with ink, ink enters the pores due to surface tension (capillary action of liquids) and is absorbed. Thus blotting paper absorb ink
Q:- Why does a small ball of iron sink in water but a large ship float?
Ans:- This is due to the Archimedes’ principle. The weight of water displaced by an iron ball is less than its own weight, whereas water displaced by the immersed portion of a ship is equal to its weight. Thus a small ball of iron sink in water but a large ship float.
Q:- Why does ice float on water?
Ans:- The weight of ice block is equal to the weight of the liquid displaced by the immersed portion of the ice, therefore the ice floats on water.Thus ice floats on water.
Q: why does moisture gather outside a tumbler containing cold water?
Ans:- This is due the principle of condensation. The water vapors in the air condense on cooling and appear as droplets of water. Therefore moisture gather outside a tumbler containing cold water.
Q:- Why does kerosene float on water?
Ans:- The kerosene float on water because the density of kerosene is less than that of water. Thus kerosene floats on water.
Q54: Why does cream rises in the milk?
Ans: The cream floats on the milk because the density of the cream is less than that of milk. Thus cream rises in milk and floats at the top.