Select the correct answer.
The average atomic mass of oxygen is 15.9994 amu. The atomic masses of its three isotopes are as follows: O-16: 15.995 amu; O-17: 16.999 amu; O-18: 17.999 amu.
Which isotope is most likely to have the greatest abundance in nature?
A. O-16
B. O-17
C. O-18
Answer (2)
The average atomic mass of oxygen is close to the atomic mass of O-16.
This indicates O-16 has the highest abundance.
Therefore, O-16 is the most abundant isotope.
The answer is A. O − 16
Explanation
Problem Analysis We are given the average atomic mass of oxygen and the atomic masses of its three isotopes. We need to determine which isotope is most likely to have the greatest abundance in nature.
Given Data The average atomic mass of oxygen is 15.9994 amu. The atomic masses of its three isotopes are: O-16: 15.995 amu O-17: 16.999 amu O-18: 17.999 amu
Reasoning Since the average atomic mass (15.9994 amu) is very close to the atomic mass of O-16 (15.995 amu), it suggests that the abundance of O-16 is significantly higher than the abundances of O-17 and O-18.
Conclusion Therefore, O-16 is most likely to have the greatest abundance in nature.
Examples
Isotopes are used in various fields, including medicine and archaeology. For example, carbon-14 dating uses the known decay rate of carbon-14 to estimate the age of organic materials. In medicine, radioactive isotopes are used in imaging techniques like PET scans to diagnose diseases. Understanding the abundance and properties of isotopes is crucial for these applications.
The isotope O-16 has an atomic mass (15.995 amu) that is very close to the average atomic mass of oxygen (15.9994 amu), indicating it is the most abundant isotope in nature. Therefore, the selected answer is A. O-16.
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