A question about acidity Since everyone knows an acid would dissociate(partially or fully) in its aqueous solution and liberate $\ce{H+}$. We also calculate the $\pu{pH}$ of the solution using $[\ce{H+}]$ and this$(\ce{H+})$ is what gives the solution acidity. Now consider we have just got a strong acid i.e pure acid without having any water in it, for example, $\ce{H2SO4}$ and no water in it, would the sulphuric acid dissociate in this case i.e without the aid of water? If it does not dissociate would this substance be acidic, since there would be no $\ce{H+}$ in that case?
Not really. Like lots of things with polar bonds, sulfuric acid can undergo ion transfer reactions in the liquid and make ionic species in solution.  And it is indeed protons that get transferred just like water.  But as with water, at least under ordinary conditions, these ionic species are only a minor portion of the liquid which is mostly $\ce{H2SO4}$ molecules.

Strong acids such as sulfuric acid are indeed acidic, capable of acting as acids.  But they still need a base with which they can react, to actually act as acids.  In the case of diluting sulfuric acid, water serves as such a base.