Heat is a form of energy which flows from hot body to cold body.
Units :- 1. Joule (J) (in S.I system)
2. Calorie(cal) (in C.G.S system)
1. The specific heat of a substance is the amount of heat required to raise the temperature of unit mass of the substance by one unit.
Units :- 1. J/Kg-K (in S.I System).
2. Cal/gm -0C (in C.G.S Unit).
1. ThE process of converting solid into a liquid is called Melting.
2. Melting point of a water is at 00C or 273K.
1. Boiling is a process in which the liquid phase changes to gaseous phase at a constant temperature at a given pressure.
2. Boiling point of a water is 1000C or 373K.
1. During the low temperature, the water molecules presents in vapour condense on the dust particles in air and form small droplets of water.
2. These droplets keep floating in the air and form a thick mist. This thick mist is called fog.
The water droplets condensed on window panes, flower, grass etc during the winter nights is dew.
1. The process in which a substance in liquid phase changes to solid phase by losing some of its energy is called freezing.
2. Freezing of water takes place at 0°C temperature and at one atmospheric pressure.
1. The phase change from gas to liquid is called condensation.
2. It is a warming process.
1. The process of escaping of molecules from the surface of a liquid at any temperature is called evaporation OR The change of phase from liquid to gas that occurs at the surface of the liquid is called evaporation.
2. Evaporation is a cooling process.