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.

Similarity. Both liquids and gases are fluids and assume the shape of the container.
Dissimilarity. A gas can be compressed easily whereas a liquid cannot. A small quantity of a gas can fill an entire given container also large quantity of a gas can be contained in a small space. A given amount of the liquid has a fixed volume at a given temperature.

Light and sound are not considered as matter because they have no mass and do not occupy space.

Water exists as solid water (ice), liquid water (water) and gaseous water (steam).The melting point of ice is 0⁰C.It does not mean that water is not available as solid at 0⁰C.It only means that at this temperature ice starts melting and at 0⁰ C both ice and water are in equilibrium.Similarly the boiling point of water as 100⁰ C does not mean that at this temperature there is no liquid water present.At 100⁰C actually both water and steam are in equilibrium.At these temperatures with a little change in energy one can move to either of the stats.This energy is called latent heat.The word 'latent' is used to signify that this heat is taken up or given by the system but not shown by rise or fall in temperature.

Evaporation is useful in our life as follows:
1.We wear cotton in summer.During summer we perspire more.These particles gain energy from body surface and due to pores in cotton clothes are able to evaporate.This keeps the body cool.
2.Wet clothes dry up in sunlight
3.After a hot sunny day, we sprinkle water on the roof or open ground because latent heat of vaporisation of water helps  us to cool the surface

At \(0°C\) , when the ice melts, the temperature of the system does not change through the heat is continuously supplied.The given heat is used up in overcoming the force of intermolecular attraction.This results in the conversion of ice into water.As this heat energy is absorbed by ice without any rise in temperature of the system, this heat is considered as hidden in the system and is known as latent heat.

Characteristics of particles matter are:
(i) Particles of matter have space between them
(ii) Particles of matter are continuously moving and thus possess kinetic energy.
(iii) Particles of matter can diffuse into one another.
(iv) Particles of matter attract each other.The force of attraction varies from one kind of matter to another.
(v) Particles of matter have mass.

A wooden chair is a solid because
(a) it is rigid.
(b) it has definite shape.

Ice at 273 K has less energy than water (although both are at the same temperature). Water possesses the additional latent heat of fusion. Hence, at 273 K, ice is more effective in cooling than water.

(a) Take a tiny crystal of dry blue ink.Ink is a matter.Dissolve it in 100mL water.The colour of water becomes blue.Dilute 1mL of this blue water with 99mL clear water.Water again becomes blue though intensity of colour decreases.Repeat 2-3 times.The solution obtained remains coloured through intensity of colour decreases gradually.This shows that one tiny crystal of link contains millions of ink particles which are very very small
(b) Add 2g salt in a cylinder containing water marked at 100mL.Salt dissolves and disappears but the volume of water remains at 100 mL mark.This means salt particles get into spaces between water particles.Water is a matter and particles of water have spaces between them.
(c) Put a drop of perfume in one corner of the room.Stand at the other end.Stil you will get smell of perfume.This is because of matter, i.e., perfume are moving with air
(d) In the above case particles of perfume and that of air intermix with each other.This intermixing of particles of two different types of matter on their own is called diffusion.
(e) Open a water tap.Try to break the stream of water with your fingers,You will find that the stream of water does not cut.This is because particles of matter attract each other with a force that keeps the particles together.