Question

i) why is the process of evaporation occurs only the surface?
ii) how does a brass-iron bimetallic strip bend on heating?
iii) give reason , evaporation is accompanied by cooling.
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Answer 1

Answer:

1.Evaporation is a type of vaporization of a liquid that only occurs on the liquid's surface. Usually, the molecules in a glass of water do not have enough heat energy to escape from the liquid. With sufficient heat, however, the liquid would quickly turn into vapor.

2.When this bimetallic strip is heated, the brass expands more than the steel and the strip curves with the brass on the outside. If the strip is cooled, it curves with the steel on the outside. Bimetallic strips are used as switches in thermostats.

3.Evaporation causes cooling because the process requires heat energy. The energy is taken away by the molecules when they convert from liquid into gas, and this causes cooling on the original surface.