Physics
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.
Related Questions
Write true or false for each statement:
(a) Evaporation is rapid on a wet day.
(b) Evaporation takes place only from the surface of a liquid.
(c) All molecules of a liquid take part in the process of evaporation.
(d) Temperature of a liquid rises during boiling or vaporization.
(e) All molecules of a liquid take part in boiling.
(f) Boiling is a rapid phenomenon.
(g) All solids expand by the same amount when heated to the same rise in temperature.
(h) Telephone wires are kept tight between the two poles in winter.
(i) Equal volumes of different liquids expand by different amounts when they are heated to the same rise in temperature.
(j) Solids expand the least and gases expand the most on being heated.
(k) A mercury thermometer makes use of the property of expansion of liquids on heating.
(l) Kerosene contracts on heating.
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 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
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