Respuesta :
Answer:
For 1: The correct answer is Option B.
For 2: The correct answer is Option D.
Explanation:
- For 1:
Average atomic mass is defined as the sum of masses of each isotope each multiplied by their natural fractional abundance.
The equation used to calculate average atomic mass follows:
[tex]\text{Average atomic mass }=\sum_{i=1}^n\text{(Atomic mass of an isotopes)}_i\times \text{(Fractional abundance})_i[/tex]
We are given:
For every 100 atoms of X, 30 of them have a mass of 125.0 u and 70 of them have a mass of 126.0 u. This means that fractional abundance of X-125 isotope is 0.3 and that of X-126 isotope is 0.7
- For X-125 isotope:
Mass of the isotope = 125
Fractional abundance of isotope = 0.3
- For X-126 isotope:
Mass of the isotope = 126
Fractional abundance of isotope = 0.7
Putting values in above equation, we get:
[tex]\text{Average atomic mass }=[(125\times 0.3)+(126\times 0.7)]=125.7u[/tex]
Hence, the correct answer is Option B.
- For 2:
We are given:
Average atomic mass of sulfur = 32.06 u
Sulfur has 4 naturally occurring isotopes: S-32, S-33, S-34 and S-36
As, the average atomic mass of sulfur lies closer to the mass of S-32 isotope. This means that the relative abundance of this isotope is the highest of all the other isotopes.
The 'S-32' isotope is the most common isotope of the given element.
Hence, the correct answer is Option D.
1. The average atomic mass of element X is 125.7 u
The correct answer to the question is Option B. 125.7 u
2. The most reasonable inference you could make about sulfur (S), which has four stable isotopes and an average atomic mass of 32.06 u is that the most common isotope of sulfur is S-32.
The correct answer to the question is
Option D. The most common isotope of sulfur is S-32.
1. Determination of the average atomic mass of X
Let A represent isotope X-125
Let B represent isotope X-126
For A (isotope X-125)
Mass of A = 125 u
Abundance of A (A%) = 30%
For B (isotope X-126)
Mass of B = 126 u
Abundance of B (B%) = 70%
Average atomic mass of X =?
Average atomic mass = [(Mass of A × A%)/100] + [(Mass of B × B%)/100]
= [(125 × 30)/100] + [(126 × 70)/100]
= 37.5 + 88.2
= 125.7 u
Thus, the average atomic mass of X is 125.7 u.
The correct answer to the question is Option B. 125.7 u
2. The average atomic mass of an element is closest to the mass of the most abundant isotope of the element.
Thus, we can conclude that the most common isotope of Sulfur is S-32 since it's average atomic mass is 32.06 u
NOTE: Stable isotopes of sulphur are: S-32, S-33, S-34 and S-36
The correct answer to the question is Option D. The most common isotope of sulfur is S-32.
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