On a bright sunny day, Riya and Gargi are playing with a ball (solid) in the park. Gargi feels thirsty. So, Riya brings tender coconut water (liquid) for her. At the same time, a strong breeze (gas) starts blowing and it also begins to rain (liquid). They run back into the house (solid), change their clothes (solid) and then their mother gives them a cup (solid) of hot milk (liquid) to drink.

Yes, the shape of the water will change because liquids do not have a shape of their own. They take the shape of the container in which they are present.

No, the shape of the stone will not change by putting it in a dish containing water because solids have definite shape. They do not change their shape and retain it, no matter whatever be the circumstances.

• Water in liquid form is used to drink by living organism.
• Ice is a solid form of water.
• In gaseous state it is a vapour.
• Boiling point and condensation point of the water is 100°C.
• The melting point and freezing point of water is 0 °C.
• Many substances can dissolve in water, therefore it is called universal solvent.

• Glass is made from silica or sand.
• Glass is a solid substance.
• Glass has the properties of Brittleness.
• If there is pressure on glass it turns into fine particles.

• Chalk is a solid substance.
• It is insoluble in water.
• Brittleness is a character of chalk.
• If pressure is applied, chalk forms fine particles.

• Iron is a solid metal.
• The iron has both malleability and ductility.
• Iron also has sonority.
• Iron has electrical conductivity and thermal conductivity. Therefore many machines are made of iron.
• The iron can be used to make sheets or wires.
• Iron is used to manufacture many equipment and articles.

• Sugar is a solid and particulate matter.
• Sugar is soluble in water.
• After dissolving in water it forms sugar solution.

• Salt is particulate, solid chemical compound.
• It is soluble in water but insoluble in kerosene.
• It is salty to taste. It forms salt solution after dissolving in water.

• Flour is particulate and solid matter which is obtained after the grains are ground finely.
• It is insoluble in water.
• By adding water to the flour, a solid substance is prepared.

• Coal is solid substance.
• Coal is inflammable substance.
• Coal is brittle in nature.
• If pressure is applied it is crushed into particles.
• Coal is used as a fuel.

• Soil is a solid substance.
• It is a mixture of many soluble and insoluble substances.

• Pen is a man-made product made from plastic and metals.
• It contains the solution of ink, so that we can write with it.

• Ink is a liquid substance.
• It can made in different colours.

• Soap is of different types. Some soaps are solid while some are in liquid form.
• Some soaps are in the form of a block while some are in the form of powder.
• Soaps are soluble in water and they form soap solution.
• Different chemicals are used to manufacture the Soaps.

Sublimation is the change of the state of solid substance directly into the gaseous state upon heating, without going through the liquid state is called sublimation. Substances show sublimation are dry ice, moth balls or napthalene balls, camphor (kapur).

A sickle to cut sugarcane- For cutting the sugarcane we need a strong equipment. Therefore stickle is made from iron or other strong metals. Hardness, malleability, and ductility are the characteristics of iron. Therefore it is ideal to use it in making of sickle.

The sheets used for roofing- Aluminium is used to make sheets for roofing because it is malleable i.e. it can be hammered into sheets. Aluminium is a metal that is light in weight and is durable and rust free. It can protect the house well from rains and sun.

A screwdriver- It is made up of good quality steel because it is very hard and durable. Steel is a mixture of different metals. It is strong and is thus helpful in joining nuts and bolts. A screwdriver is essential and convenient tool for many work.

A pair of tongs- Now a days it is made up of metals like stainless steel or aluminium because they are durable, strong and rust free. They have high melting points and do not melt while using on flames. Usually in a kitchen this equipment is used and hence it is made from high quality metals.

Electric cables- Electric cables are either of copper or aluminium. Copper is a good conductor of electricity. Therefore, most of the electric cables are made from copper.

Ornaments- Metals such as gold and silver are used for making Ornaments because they are very lustrous. Nowadays platinum is also used for making ornaments. All these metals have characteristic of ductility. Hence they can be stretched and pulled in the form of wires. Making ornaments from these metals thus becomes easier. Diamonds are also studded in ornaments. Diamond is the hardest substance and has shine.

Pots and pans- Pots and pans are made from different type of metals. Aluminium, stainless steel and brass are the common choices. Cooking food becomes easier in them. All the metals have a characteristic of thermal conductivity. In pots of stainless steel, the chemical reactions with the food do not take place. Therefore, it becomes convenient to use such material.

If nails are made out of plastic, they cannot be used for its usual purposes. Nails should be made from metals that have characteristic of hardness. Plastic is a brittle substance. It cannot withstand hammering, neither it can enter the material in which we may try to pierce them. Therefore nails made of plastic cannot be used.

If a bell is made of wood, it will not ring.

• The bells are made up of metals like copper etc. as they show the property of sonority i.e. the ability to produce a ringing sound when striked upon.
• The sound produced by metal bell would be melodious.
• Similar sound cannot be produced by wooden bell as wood does not have characteristic of sonority.

Tongs are made up of metals and they have the ability to conduct heat. If they are fitted with rubber, the heat will be transfered to the rubber, they may cause burns. This can hurt us.

• Knife is used to cut vegetables, fruits etc.
• The regular knifes which we use are made up of metals like iron etc. as they are hard, strong and durable.
• Also they can be sharpened and moulded into shapes which we desire.
• The wood is not metal and is thus not hard.
• The work of knife cannot be performed by the wooden knife. It cannot cut the objects due to lack of hardness.

An axe is used to cut and chop wood. Rubber is a substance having elasticity. The rubber axe will rebound when hit upon an object. The metal axe can perform a function as the metals are hard substances. The rubber axe will not be able to do this function.

(a) I’m found in a thermometer, I measure your temperature- Mercury
(b) I make things hot or cold- Heat
(c) I have no shape whatsoever !- Liquid and Gas
(d) I dissolve in water, but not in kerosene- Salt

In winter, the temperature of air is less. At this temperature the freezing point of coconut oil is reached. Therefore it freezes and appears to be thickened.

Kerosene left open in a dish disappears because it is a volatile compound. It quickly evaporates. The temperature of the surrounding accelerates this process of evaporation and thus the kerosene completely evaporates and disappears, if it is kept in open.

When the incense stick is lighted, it releases smoke which contains the fragrance. Smoke is a form of gas which quickly spreads in the entire room along with the fragrance and thus making the entire room fragrant.

The picture shows two things which are present in tub of water. One is a balloon which floats on the surface of the water while the other is an apple which sinks to the bottom of the tub. The balloon floats on the surface of the water because it is filled with air, i.e. a gaseous substance. It has less density as compared to the density of the water whereas the apple sinks to the bottom of the tub because apple is a solid substance, it has more density than water.