The best known example of a naturally-occurring radioisotope is uranium. All but 0.7 per cent of naturally-occurring uranium is uranium-238; the rest is the less stable, or more radioactive, uranium-235, which has three fewer neutrons in its nucleus.
The question requires us to use the dilution formula , where and are the stock concentration and volume respectively, then and are the dilute concentration and volume respectively.
a. = 1.5 M KCI, =0.20M KCl, =250ml KCl
b.
To prepare the solution 33.3ml of 1.5M KCl is diluted to a total final volume of 250ml.