how do i prepare a sulphuric acid solution having 75 % purity with 1.68 specific gravity from sulphuric acid with 97 % purity and 1.834 specific gravity.

Answer 1

This may be the long way around but here is what I would do. I would determine the M of each solution.
1.68 x 1000 x 0.75 x (1/98) = approx 13 M but you need a more exact number.
1.834 x 1000 x 0.97 x (1/98) = approx 18 M

First, how much do you want to prepare. Let's say 1000 mL.
mL1 x M1 = mL2 x M2
1000mL x 13M = mL2 x 18M
Solve for mL2 = approx 722 mL. Therefore, place some water in a 1000 mL volumetric flask, CAREFULLY add 722 mL of the more concentrated solution (be very careful because it will get quite hot), let it cool, add water to the mark of the flask, mix thoroughly, stopper.