Chemistry

Question Analysis
This question involves calculating the average atomic mass of an element with three isotopes.
The main focus is on applying the weighted average formula (mass × decimal abundance for each isotope, then summing) and rounding to two decimal places.

Key Concept Explanation
Average atomic mass = (Mass of Z-62 × Abundance₁) + (Mass of Z-63 × Abundance₂) + (Mass of Z-64 × Abundance₃)
Abundances must be converted from percentages to decimals (divide by 100) before calculation.

Step-by-Step Solution
1. Convert abundances to decimals:
Z-62: 69.17% = 0.6917
Z-63: 21.92% = 0.2192
Z-64: 8.91% = 0.0891
2. Calculate each isotope’s contribution:
Z-62: 61.93 amu × 0.6917 = 61.93 × 0.6917 = 42.836981 amu
Z-63: 62.93 am...