Physics
In evaporation:
- all molecules of liquid begin to escape out
- only the molecules at the surface escape out
- the temperature of liquid rises by absorbing heat from surroundings
- the molecules get attracted within the liquid
Answer
only the molecules at the surface escape out
Reason — In evaporation, some molecules near the surface of liquid acquire sufficient kinetic energy by collisions with the other molecules, to reach the surface. These molecules absorb heat from the surroundings to escape out in space.
Related Questions
Fill in the blanks:
(a) Boiling occurs at …………… .
(b) Evaporation takes place at …………… .
(c) The molecules of liquid …………… heat from surroundings in evaporation.
(d) Heat is …………… during boiling.
(e) Cooling is produced in …………… .
(f) A longer rod expands …………… than a shorter rod on being heated to the same temperature.
(g) Liquids expand …………… than the solids.
(h) Gases expand …………… than the liquids.
(i) Alcohol expands …………… than water.
(j) Iron expands …………… than copper.
Match the following:
Column A Column B (a) Blowing air increases (i) increase in inter-molecular separation (b) Increase in pressure increases (ii) pendulum of a clock (c) Thermal expansion (iii) cooking utensils (d) Invar (iv) boiling point (e) Pyrex glass (v) evaporation The rate of evaporation of a liquid increases when:
- temperature of liquid falls
- liquid is poured in a vessel of less surface area
- air is blown above the surface of liquid
- humidity increases
During boiling or vaporization:
- all molecules take part
- temperature rises
- no heat is absorbed
- the average kinetic energy of molecules increases