4th Class Science Matter and Materials States of Matter

       States of Matter

Matter is divided into three groups according to the state in which they exist.

           Solid

In solids, the molecules are very close to one another and the force of attraction among the molecules is great.

Arrangement of molecules in solid

Because of this close packing and great attraction among the molecules, solids are hard and has a definite volume and definite shape. For example, ice, book, table, etc.

 Books                                           Furniture                               Animals                              Plant    

         Liquids

In liquids, the molecules are not packed very close. They can move about more freely because of less attraction among them.

Arrangement of molecules m liquid

This is the reason for the liquid to flow. So liquid has no definite shape but a definite volume. It takes the shape of the container in which it is put. For example water, milk, cold drink, petrol etc.  

   Water                                            Milk                               Petroleum                                  Cold drink  

         Gas

In gases, the molecules are far apart from one another. They have lots of freedom to move. Hence gas has neither fixed shape nor fixed volume.  

Arrangement of molecules in gas  

Water vapour, smoke etc.

  Look at the following figure carefully and choose the correct option for it.

(a) Gas 

(b) Liquid

(c) Solid

(d) Both A and C

(e) All the above

Answer: (c)

      In gases, the molecules are separated by large spaces and they have freedom to move about. This gives them their character that is

(a) No definite shape

(b) No definite volume

(c) Definite volume 

(d) (a) and (b)

(e) None of these

Answer: (d)