Which of the following is closest to the natural abundance of the isotope Br-79?

• A. 75.4%
• B. 10.2%
• C. 50.7%
• D. 23.1%

Answer: (C)

Verified step by step guidance

1. Understand that natural abundance refers to the percentage of a specific isotope found naturally in a sample of an element.
2. Recall that bromine (Br) has two main isotopes: Br-79 and Br-81, and their natural abundances must add up to 100%.
3. Recognize that the natural abundance of Br-79 is approximately half of the total bromine isotopes, so it should be close to 50%.
4. Compare the given options (75.4%, 10.2%, 50.7%, 23.1%) to the expected value near 50%, identifying 50.7% as the closest to the natural abundance of Br-79.
5. Confirm that the natural abundance values are consistent with known isotopic distributions for bromine, where Br-79 and Br-81 are roughly equally abundant.