Question

Give reasons for the following. [5 MARKS]
a) People often breathe out on the glasses of their spectacles for cleaning.
b) A bottle of cold water kept outside refrigerator, shows puddle of water around it.
c) Fog is seen in cold winter mornings.

Answer 1

a) 2 Marks
b) 2 Marks
c) 1 Mark

a) The moist air coming out from mouth condenses on the glasses and makes them wet. This makes the cleaning process easy.
b) The cool surface of the cold bottle cools the air around it and the water vapours of the air condense on the surface of the bottle. This is the reason of the water around a bottle of cold water.
c) When air is cooled to the dew point, fog droplets form. When the air temperature is the same as the dew point temperature, condensation occurs on tiny particles floating in the air.