Answer:
Percent abundance of ¹²²X is 13%
Explanation:
The ¹²⁰X has a mass of 120 amu and ¹²²X has a mass of 122 amu. The average atomic mass is:
Average: 120.26amu: X*120amu + Y*122amu (1)
Where X is percent abundance of ¹²⁰X and Y percent abundance of ¹²²X
That means you can also write:
X + Y = 1 (2)
Because the sum of both percentages is 100%
Replacing (2) in (1):
120(1-Y) + 122Y = 120.26
120 - 120Y + 122Y = 120.26
2Y = 0.26
Y = 0.13 = 13%
That means percent abundance of ¹²²X is 13%
