Final Answer:
The average atomic mass of the unknown element X is C. 107.8636 amu.
Step-by-step explanation:
The average atomic mass is a weighted average of the masses of an element's isotopes, considering their abundance. In this case, option C (107.8636 amu) represents the closest value to the actual average atomic mass of element X. To calculate this, you would multiply the mass of each isotope by its abundance, summing up these values for all isotopes. Option C provides the most accurate representation of this calculation compared to the other given choices.
To elaborate, option A (106.9 amu) and option B (108.9 amu) are slightly off from the accurate average, indicating a potential miscalculation or inaccuracy. Meanwhile, option D (51.82 amu) is significantly lower than the expected range for atomic masses, suggesting a fundamental error in the provided values.]
Therefore, based on the principles of atomic mass calculations, option C is the most plausible and accurate representation of the average atomic mass for the unknown element X, aligning closely with theoretical expectations.