Naturally occurring indium has two isotopes, indium-113 (112.9040580 amu) and Indium-115 (114.9038780 amu. The atomic mass of indium is 114.82 amu. What is the percent of indium-115? a) 4.32% b) 48.4% c) 95.7% d) 0.973%

The answer to your question is: letter c (96%)

Explanation:

Indium - 113 (112-9040580 amu) ₁₁₃In

Indium-115 (114.9038780 amu) ₁₁₅In

Atomic mass of Indium is 114.82 amu ₁₁₄.₈₂In

Formula

Atomic mass = m₁ (%₁) + m₂ (%₂) / 100

%₁ = x I established this is an equation

%₂ = 100 - x

Substituting values

114.82 = 112.8040x + 114.9039 (100-x) / 100 and know we expand and simplify

114.82 = 112.8040x + 11490.39 - 114.9039x / 100

11482 = 112.8040x - 114.9039x + 11490.39

11482 - 11490.39 = 112.8040x - 114.9039x

-8.39 = - 2.099x

x = 3.99

Then % of Indium-115 = 100 - 3.99 = 96