Steam, is more energetic than boiling water, can produce severe burns.

Atmospheric gases can be liquefied if a high pressure is applied at some low temperature.

Blue colour of copper sulphate spreads faster in beaker A, i.e., Diffusion is faster in hot water.

In the container, the gaseous particles are free to move.These move at high speed and collide with other particles or walls of the container.The bombardment of the particles on the walls of the container produces a steady force that depends on the temperature.This force per unit area is called as pressure of the gas.

A gas is highly compressible and a large quantity of it can be compressed to a small manageable volume.Therefore, natural gas is compressed and is supplied for use by vehicles in the name of CNG(compressed natural gas)

1. Solids have melting and boiling points above room temperature.
2. Liquids have melting points below room temperature and boiling point above room temperature.
3. Gases have melting and boiling points below room temperature.

(i) Rate of diffusion decreases with density of a liquid.Honey is denser than ink.If you add a drop of ink and honey in two separate jars filled with water, it will be observed that honey takes longer time to reach the bottom of the jar as compared to that taken by ink.
(ii) Diffusion increases with rise of temperature.For example, liquids mix faster at higher temperatures.

Air is matter because it has mass and occupies space.

The substances are not classified only by their appearances.These are classified by their properties such as density, boiling point or melting point, conductivity, thermal capacity and other chemical properties.sugar and sodium chloride have different physical and chemical properties and so are different substances.

A substance occuring in nature or coming in use in day to day life is called matter.Examples are naturally occuring minerals, plants to paper, chalk, coke, food etc.a matter may be available in varieties of shape, size, colour and odoour.Matter is thus anything that has and occupies space.