A chemist wants to make a solution of 3.4 M HCl. There are two solutions of HCL that he can find on the shelf. One has a concentration of 6.0 M, while the other has a concentration of 2.0 M. Which solution can the chemist use to make the desired acid?

Answer 1

Technically the chemist can use either; however, the 2.0M would need to be evaporated to arrive at a more concd solution and that isn't practicable.
The 6.0 M solution can be diluted to make a 3.4M soln.
If you want to calculate, use
c1v1 = c2v2, the dilution formula.
c = concn
v = volume