9.Why do in summer, roads often appears to be covered with water when seen from a distance?Explain.

This is due to total internal reflection.In summer during the day time the layers of the air in contact with road becomes very hot while upper layers of the air comparatively cool.The light travels from upper cold layers(denser medium)to lower hot layers(rarer medium)So,it is refracted away from the the normal when the angle of incidence is greater than the critical angle,total internal reflection takes place and the light is reflected .when the refracted rays enter in our eyes roads appears as a pool of water.This pool of water is the image of sky.So, in summer, roads often appears to be covered with water when seen from a distance.