what's normality and equivalent weight and what are they used for???(acc. to 11th std)??

Take two glasses of water. Add one spoon of sugar to one glass and two spoons of sugar to the other. The second one is much more sweeter than the first because it contains double the amount of solute. The two solutions are said to differ in their concentrations.

Concentration of a solution is measured in various units such as Normality, Molarity and Molality.

Normality is the concentration of a solution; that tells us the number of gram equivalents of solute present in every litre of solution.

Gram equivalent is the equivalent weight expressed in grams. To understand it you have first understand the meaning of equivalent.

Chemical substances do not react with each other in terms of moles. It means, 1 mole of A may react with 2 moles of B or with 3 moles of C or with X moles of Z. The proportion in which they react is uncertain, until and unless you know the stoichiometry of the reaction.

To avoid this ambiguity of proportions of reactants, chemists introduced the concept of Equivalent weights. Always one equivalent of one substance reacts with one and only one equivalent of the other substance. Means, chemical substances react in terms of their equivalents (or milli equivalents) and not in terms of moles. 

Gram equivalent of an acid, base, reductant  or oxidant is the mass of substance in gram that can transact Avagadro number of electrons. So, 1 equivalent of acid reacts with 1 eq of base or 1 eq of reductant reacts with 1 eq of oxidant.