Question

Which of the following student's statements is correct regarding the abundances of the isotopes of lithium?

A. Student 2 says that lithium-7 is more abundant since the atomic mass of lithium is 6.94 amu and the more abundant an isotope, the closer the atomic mass will be to the mass of that isotope.
B. Student 4 says that lithium-6 is more abundant since the atomic mass of lithium is 6.94 amu and the more abundant an isotope, the closer the atomic mass will be to the mass of that isotope.
C. Student 3 says that lithium-6 is less abundant since the atomic mass of lithium is 6.94 amu and the more abundant an isotope, the farther the atomic mass will be from the mass of that isotope.
D. Student 1 says that lithium-7 is less abundant since the atomic mass of lithium is 6.94 amu and the more abundant an isotope, the farther the atomic mass will be from the mass of that isotope.

Answer 1

The correct statement is A, which says lithium-7 is more abundant as the atomic mass of lithium is 6.94 amu and more closely aligned with the mass of the more abundant isotope, lithium-7.

Step-by-step explanation:

The correct statement regarding the abundances of the isotopes of lithium is Student 2's statement. According to Student 2, lithium-7 is more abundant because the atomic mass of lithium is 6.94 amu and the more abundant an isotope is, the closer the atomic mass will be to the mass of that isotope.

This matches the information provided, which states that naturally occurring lithium consists of about 92.5% lithium-7 and 7.5% lithium-6. Considering that the atomic mass of lithium is closer to the mass of lithium-7 (7.01600 amu), it indicates that lithium-7 is indeed the more abundant isotope over lithium-6, which has a mass of 6.01512 amu.