Answer:
Wt Avg of the two isotopes = 235.62 amu
Explanation:
Given:
abundance
Isotope % fractional mass (amu) Wt. Avg. Contributions
Z234 19% 0.19 234 (0.19)(234) = 44.46 amu
Z236 81% 0.81 236 (0.81)(236) = 191.16 amu
Collective Wt. Avg. of all isotopes = ∑ Wt. Avg. Contributions
= 44.46 amu + 191.16 amu = 235.62 amu