Weight of sodium thiosulfate = 76.148 - 8.2
= 67.948 g.
Concentration of the solution = 67.948 / 172.7
= 0.393 g / mL. to the nearest thousandth . (answer).
The two stable isotopes of lithium are Lithium 6 with three neutrons and lithium 7 with four neutrons. Lithium 7 is the predominant isotope, about 92.5%.