Properties of Materials
We generally use a tumbler to keep a liquid. A tumbler cannot be made from cloth. We need a tumbler made from glass, plastics, metal or other such material that will hold water. Similarly, it would not be wise to use paper-like materials for cooking vessels.

Using a cloth tumbler

we choose a material to make an object depending on its properties, and the purpose for which the object is to be used. 
Some properties are discussed here.
(i)    Appearance :
Materials usually look different from each other. Wood looks very different from iron. Iron appears different from copper or aluminium. At the same time, there may be some similarities between iron, copper and aluminium that are not there in wood.

Activity–2
AIM :  To show that certain materials have lustre.
Material required : (i) Small pieces of paper (ii) cardboard (iii) a thin piece of wood (iv) a small strip of plastic (v) thin wires of copper, aluminium and iron (vi) heavy scissors or a metal cutter 
(vii) sand paper.
Method :
(a) Cut each of the materials with heavy scissors or metal cutter. Carefully observe the cut surface of each material.
We will notice that in case of paper card board, wood plastic, etc., the cut surface is not shining.
However, in case of thin wires of copper, aluminium and iron, the cut surface is shining.
(b) Rub each of the material with sand paper. Carefully observe the sand papered surface of the material.
We will notice that in case of paper cardboard, plastic and wool, the sand papered surface is not shining.
However, in case of thin wires of copper, aluminium and iron, the sand papered surface is shining.
So it is cleared that certain materials like metals have lustre.

(ii)    Hardness :
 When we  press different materials with our hands, some of them may be hard to compress while others can be easily compressed.
 Materials which can be compressed or stretched easily are called soft while some other materials which are difficult to compress are called hard. For example, cotton or sponge is soft while iron is hard.

(iii)    Solubility : 
Some substances like sugar, salt etc. completely disappear or dissolve in water. These substances are soluble in water. Other substances like sand, chalk powder etc. do not mix with water and do not disappear even after we stir for long time. These substances are insoluble in water.
Water plays an important role in the functioning of our body because it can dissolve a large number of substances.

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