Indium (In) is made up of 95.7% 115In and 4.3% 113In. The atomic mass of 113In is 112.904 amu. The atomic mass of 115In is 114.904 amu. What is the average atomic mass of a sample of indium?

a. 113.909 amu

b. 114.5 amu

c. 114.818 amu

d. + 666+115.00 amu

The sample of indium, has an average atomic mass of 114.818 amu

Explanation:

Step 1: Data given

Indium is made of 95.7 % 115In and 4.3% 113In

113In has an atomic mass of 112.904 amu

115In has an atomic mass of 114.904amu

Step 2: Calculate the average atomic mass

The average atomic mass = X

0.957 * 114.904 + 0.043 * 112.904 = X

109.963 + 4.855 = X

X = 114.818

The sample of indium, has an average atomic mass of 114.818 amu