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Answer:
m = 671 grams
Explanation:
Given that,
No of moles, n = 4.9
Molar mass of Barium, M = 137 g
Mass divided by molar mass is equal to no of moles. It can be given by the formula as follows :

or
m = 671 grams
So, the total mass of the sample of Barium is 671 grams.
Answer:
Average atomic mass of uranium= 237.98 amu.
Explanation:
Given data:
Abundance of U²³⁴ = 0.01%
Abundance of U²³⁵ = 0.17%
Abundance of U²³⁸ = 99.28%
Average atomic mass = ?
Solution:
Average atomic mass of uranium = (abundance of 1st isotope × its atomic mass) +(abundance of 2nd isotope × its atomic mass) +(abundance of 3rd isotope × its atomic mass) / 100
Average atomic mass of uranium= (234×0.01)+(235×0.71)+(238×99.28)/100
Average atomic mass of uranium= 2.34 + 166.85 + 23628.64 / 100
Average atomic mass of uranium= 23797.83 / 100
Average atomic mass of uranium= 237.98 amu.