Question Detail
Question
Naturally occurring gallium consists of 60.4% gallium-69 (68.93 amu) and 39.6% gallium-71 (70.92 amu). Calculate the relative atomic mass of gallium.
Correct Answer
Option A is the correct answer.
Detailed Explanation
Average atomic mass = (0.604 × 68.93) + (0.396 × 70.92) = 41.63 + 28.08 = 69.71 amu ≈ 69.7.
Hint
Multiply each isotope's mass by its fractional abundance and sum the results.