Cesium has 39 known isotopes ranging from mass 112 to 151. If a sample of cesium containing only 133Cs (132.905 amu) and 135Cs (134.906 amu) has an average atomic mass of 134.3, what is the percent abundance of 133Cs in the sample?

A hypothetical element X is found to have an atomic weight of 37.45 amu. Element X has only two isotopes, X-37 and X-38. The X-37 isotope has a fractional abundance of 0.7721 and an isotopic mass of 37.24. What is the isotopic mass of the other isotope?

An element has two isotopes, X1⁹ and X²¹. If the mass of element X is 20.2u, determine the percentage abundance of each type of isotope. Text

1) Antimony occurs in nature as a mixture of 2 isotopes. Sb-123 and Sb-121. If the Sb 121 has a mass of 120.9 amu and an abundance of 57.25%, and the average amu is 121.75, what is the abundance of the other isotope?

What is the average atomic mass of chlorine if the mass of one isotope is 34.97 amu and has a per cent abundance of 75.77%. The other isotope has a mass of 36.97 amu and has a percent abundance of 24.23%. You should do a calculation and not just look at the periodic chart.      35.45 amu     35.97 amu     34.97 amu     71.95 amu

suppose an element consisted of two isotopes with the masses 89.9 amu and 91.1 amu. If 1.500 x 10^-3 moles of this element is found to contain of 5.49 x 10^-4 moles of the isotope with the mass of 89.9 amu, what is the average atomic mass of this element

Boron (B) has two naturally occurring isotopes: boron-10 (abundance = 19.8%, mass = 10.013 amu) and boron-11 (abundance = 80.2%, mass = 11.009 amu). Calculate the atomic mass of boron.

6. Calculate the atomic mass of a cosmic sample of silicon. The three silicon isotopes have atomic masses and relative abundances of 27.9769 amu (80.2297%), 28.9765 amu (12.6832%) and 29.9738 amu (7.0872%).

There are only two naturally-occuring stable isotopes of antimony, the masses of which are listed in the table below. Use whatever data you need from the ALEKS Periodic Table to calculate the natural abundance of each isotope and complete the table. Round your entry for isotope 121 Sb 123 Sb 121 Sb to 3 significant digits and your entry for mass (amu) 120.90 122.90 natural abundance []% Про x10 X 123, Ś Sb to 3 significant digits.

The element lanthanum has an atomic weight of 139 and consists of two stable isotopes lanthanum-138 and lanthanum-139.The isotope lanthanum-138 has a mass of 138 amu and a percent natural abundance of 8.90×10-2 %.The isotope lanthanum-139 has a percent natural abundance of 99.9 %.What is the mass of lanthanum-139?