Question

Element X has 2 naturally occurring isotopes. Its first isotope has an atomic mass of 40.00 amu and a natural abundance of 74.18%. Its second isotope has an atomic mass of 41.10 amu. What is the atomic mass of element X?

A) 40.59 amu
B) 41.00 amu
C) 41.28 amu
D) 41.55 amu

Answer 1

The atomic mass of element X is calculated by averaging the masses of its isotopes, each weighted by their natural abundance. The result of the calculation is 40.30 amu, rounded to two decimal places, which does not match any of the options given exactly.

Step-by-step explanation:

To calculate the atomic mass of element X, we need to consider the contributions of both isotopes based on their natural abundances and atomic masses. The atomic mass of element X is found by multiplying the atomic mass of each isotope by its percent abundance (expressed as a decimal), and then adding these values together.

The calculation for the atomic mass of element X with its two isotopes is as follows:

(0.7418 × 40.00 amu) + ((1 - 0.7418) × 41.10 amu) = 29.672 amu + 10.6268 amu = 40.2988 amu

The atomic mass of element X, after rounding to two decimal places, is 40.30 amu. This is not exactly one of the options given, which might indicate an issue with the question itself or the options provided.