Matter in Our Surrounding Test - 11

During sublimation, naphthalene being sublime changes into vapours leaving behind impurities. Vapour can be cooled by condensation.The impure sample of naphthalene can be purified by the sublimation process.

All the statements are correct because the rate of evaporation of liquid can be accelerated by increasing the surface area, increasing wind speed and increasing the temperature. 

During the change of state of a substance, latent heat is absorbed. The latent heat does not increase the kinetic energy of the particles of the substance.

Being lower vapour pressure ether starts evaporating faster than alcohol. Diethyl ether evaporates faster than that of ethyl alcohol because the vapour pressure of ether is greater than that of alcohol.

The rate of evaporation depends upon the surface area available for evaporation. If the equal volume of ethanol is kept in a test tube, china dish, water glass and conical flask, alcohol evaporates faster in China dish having greater surface area.

Evaporation causes cooling effect because the heat of evaporation is absorbed by the surroundings. Evaporation of acetone present in nail polish remover absorbs the latent heat from the nail Causing cooling of a  nail.

(1) The process of melting, that is, change of solid state into liquid state is also known as fusion. E.g. Conversion of ice into water. 
(2) Vaporisation is the change of liquid state into gaseous state. E.g. Conversion of water into water vapour/steam.
(3) Condensation is the change of vapour state into liquid state. E.g. Change of water vapour/steam into water droplets.
(4) Change of liquid state into solid state is called solidification or freezing. E.g. Change of water into ice.

(1) A change of state directly from solid to gaseous without changing into liquid or vice versa is called Sublimation. E.g. Naphthalene, camphor and ammonium chloride change directly from solid state to gaseous state, and vice-versa, without changing into the liquid state.
(2) Evaporation is a change of liquid state into vapours below the boiling point of the liquid. It is a surface phenomenon, and produces the effect of cooling.
(3) Latent heat of vaporisation is the heat energy required to change 1 kg of a liquid to gas at atmospheric pressure at its boiling point.
(4) Latent heat of fusion is the amount of heat energy required to change 1 kg of solid into liquid.

1. The intermixing of particles of two different types of matter on their own is called diffusion. On heating, diffusion becomes faster. The rate of diffusion of gases also varies inversely as the square root of their densities. 
2. The temperature at which a liquid changes into vapour is called its boiling point. 
3. The temperature at which a solid melts to become a liquid at the atmospheric pressure is called its melting point. The melting point of a solid indicates the strength of the force of attraction between its particles.
4. The energy possessed by the particles of matter by virtue of their motion is called their kinetic energy,

(1) Boiling point of water - (C) 373K ( 373-273 = 100^∘c)

(2) Melting point of water - (B) 273K ( 273-273 = 0^∘c )

(3) Boling point of Acetone - (D) 56^∘c

(4) Melting point of Aluminium - (A) 660^∘c