Question

A certain sample of element Z contains 60% of ${}^{69}Z$ and 40% ${}^{71}Z$ . What is the relative atomic mass of element Z in this sample?

• A. 69.2
• B. 69.8
• C. 70
• D. 70.2

Answer 1

Answer: (B)

69.8

The relative atomic mass of element Z $=\frac{60\times 69+40\times 71}{60+40}=69.8$ g/mol.