Nature and Characteristics of Matter - Practice Questions & MCQ

Chemistry deals with the composition, structure, and properties of matter. These aspects can be best described and understood in terms of basic constituents of matter: atoms and molecules. That is why chemistry is called the science of atoms and molecules.

Chemistry plays a central role in science and is often intertwined with other branches of science like physics, biology, geology, etc. Chemistry also plays an important role in daily life. Chemical principles are important in diverse areas, such as weather patterns, the functioning of the brain, and the operation of a computer. Chemical industries manufacturing fertilizers, alkalis, acids, salts, dyes, polymers, drugs, soaps, detergents, metals, alloys and other inorganic and organic chemicals, including new materials, contribute in a big way to the national economy. Chemistry plays an important role in meeting human needs for food, health care products, and other materials aimed at improving the quality of life.

Anything which has mass and occupies some space is called matter. On the basis of shape, size, and volume, the matter can be classified into solids. liquids and gases.

1. Solids have definite volume and definite shape. 

2. Liquids have a definite volume but no definite shape. They take the shape of the container in which they are placed. 

3. Gases have neither a definite volume nor a definite shape. They completely occupy the container in which they are placed. 

These three states of matter are interconvertible by changing the conditions of temperature and pressure.

On heating, a solid usually changes to a liquid and the liquid on further heating changes to the gaseous ( or vapor) state. In the reverse process, a gas on cooling liquifies to the liquid, and the liquid on further cooling freezes to the solid.

CLASSIFICATION OF MATTER

CLASSIFICATION OF MATTER:

1. Physical Classification: Based on the physical state under ordinary conditions of temperature and pressure, matter is classified into the following three types-   

   1. Solid: A substance is said to be solid if it possesses a definite volume and a definite shape. 

      • e.g. sugar, iron, gold, wood, etc. 

   2. Liquid: A substance is said to be liquid if it possesses a definite volume but no definite shape. They take up the shape of the vessel in which they are put. 

      • e.g. water, milk, oil, mercury, alcohol, etc.

   3. Gas: A substance is said to be gas if it neither possesses a definite volume nor a definite shape. This is because they fill up the whole vessel in which they are put.

      • e.g. hydrogen(H₂), oxygen(O₂), carbon dioxide(CO₂), etc.

2.  Chemical Classification :

   1. Pure Substance: A material containing only one type of substance. Pure Substances can not be separated into simpler substances by physical methods.  

      eg: Element = Na, Mg, Ca, etc.         Compound = HCl, H₂O, CO₂, HNO_3, etc.

      1. Element: The pure substance containing only one kind of atoms. Depending on the physical and chemical property, these are of three types

         1. Metal 

         2. Non-metal 

         3. Metalloids

      2. Compound: It is defined as a pure substance containing more than one kind of atoms that are combined together in a fixed ratio by weight and which can be decomposed into simpler substances by the suitable chemical method. The properties of a compound are different from those of its components. 

         • e.g.: H₂O, HCl, HNO₃, etc.

3. Mixture Substance: A material that contains more than one type of substance which are mixed in any ratio by weight is called a mixture. The property of the mixture is the property of its components. The mixture is separated by simple physical method.

   1. Homogeneous mixture:  The mixture, in which all the components are mixed uniformly is called a homogeneous mixture.

      • e.g. : Water + Salt, Water + Sugar, Water + alcohol.

   2. Heterogeneous mixture: The mixture in which the composition is nonuniform is called as Heterogeneous mixture. 

      •  e.g. : Water + Sand, Water + Oil