Anything that has mass and occupies space is matter. There are three different physical states of matter - solid, liquid and gas. A particular state of matter can be changed into other states by changing the temperature or pressure.

A solid has a definite size and shape which do not change on their own. A liquid has a definite size or volume and it takes shape of the container in which it is kept. A gas has no shape or size of its own. It occupies entire volume of the container in which it is kept.

Matter can be classified on the basis of its composition as element, compound or mixture. An element is a basic form of matter that cannot be chemically broken down into simpler substances. A compound is a pure substance made from two or more than two elements chemically combined together in a definite proportion by mass.

A homogeneous mixture is a mixture where the substances are completely mixed together and are indistinguishable. A homogeneous mixture is called a solution. A heterogeneous mixture is a mixture where the substances remain separate and the composition is not uniform.

A suspension is a heterogeneous mixture where the dispersed particles are large enough to settle out eventually.

Solution: The substance which is present in bigger quantity is normally taken as solvent and substance which is present in smaller quantity is normally taken as solute.

Concentration of a solution: It is defined as the mass of solute present in a definite volume of the solution. It may also be expressed in terms of percent by mass of solute in gram. For example, a solution of 5% sugar by mass means that 100 gram of the solution contains 5 gram of sugar.

Suspensions: Materials of smaller particle size, insoluble in a solvent but visible to naked eyes form suspension. The size of particles in suspension is over 1000 nanometers.