Earlier the concept of equivalent weights was very common and the concentrations of the solutions were expressed in terms of normalities. The convenience was that the substances reacted in the ratio of their gram equivalents . So there was no need to write balanced equation to determine the amounts of the substraces reacted. However, determination or equivalent weights posed difficulty in certain cases. Moreover, the equivalent weight of the same substance is not same in different reactions, For example, KMnO_(4) has different equivalent weight in the basic medium than inthe acidic medium. Hence, now a days, mole concept is more common and the concentrations of the solutions are generally expressed in terms of molarities, though some other methods like molality. mole fraction etc. are also used. The volume of the above solution required to make 1.0 L of 0.10 M HCl will be