1) The element indium has two common isotopes: In-113 and In-115. If the relative atomic
mass of indium is 114.8, determine the isotopic abundances of In-113 and In-115.

2) The element cerium has 4 naturally-occurring isotopes: 0.185% Ce-136, 0.251% Ce-138.
88.45% Ce-140 and 11.114% Ce-142. Determine the relative atomic mass of cerium.

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