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ICSE-VIII-Physics

06: Heat Energy Class 8 Physics

with Solutions - page 4
Qstn# B-9 Prvs-QstnNext-Qstn
  • #9
    Give reason for the increase in rate of evaporation of a liquid when (a) air is blown above the liquid (b) surface area of liquid is increased (c) temperature of liquid is increased. (a) air is blown above the liquid (b) surface area of liquid is increased (c) temperature of liquid is increased.
    Ans : (a) Blowing Air on Liquid surface increase rate of evaporation: Blowing air takes away with it the molecules of liquid escaping out of the surface. To take their place, other molecules escape out from the surface of liquid. (b) Surface area increases the rate of evaporation: On increasing the area of the surface, number of molecules escaping out from the surface increases. (c) Increase in temperature increases the rate of evaporation: Increase in temperature increases K.E.
    (K.E = 1/2 Mv2). More and more molecules come to the surface of liquid hence the rate of evaporation will increase with increase in temperature. (a) Blowing Air on Liquid surface increase rate of evaporation: Blowing air takes away with it the molecules of liquid escaping out of the surface. To take their place, other molecules escape out from the surface of liquid. (b) Surface area increases the rate of evaporation: On increasing the area of the surface, number of molecules escaping out from the surface increases. (c) Increase in temperature increases the rate of evaporation: Increase in temperature increases K.E.
    (K.E = 1/2 Mv2). More and more molecules come to the surface of liquid hence the rate of evaporation will increase with increase in temperature.
  • #9-a
    air is blown above the liquid
    Ans : Blowing Air on Liquid surface increase rate of evaporation: Blowing air takes away with it the molecules of liquid escaping out of the surface. To take their place, other molecules escape out from the surface of liquid.
  • #9-b
    surface area of liquid is increased
    Ans : Surface area increases the rate of evaporation: On increasing the area of the surface, number of molecules escaping out from the surface increases.
  • #9-c
    temperature of liquid is increased.
    Ans : Increase in temperature increases the rate of evaporation: Increase in temperature increases K.E.
    (K.E = 1/2 Mv2). More and more molecules come to the surface of liquid hence the rate of evaporation will increase with increase in temperature.