1) Assume element X has 2 isotopes: X-125 and X-126. For every 100 atoms of X, 30 of them have a mass of 125.0 u and 70 have a m

Question

9 days ago

12

1) Assume element X has 2 isotopes: X-125 and X-126. For every 100 atoms of X, 30 of them have a mass of 125.0 u and 70 have a m

ass of 126.0 u. What is the average atomic mass of X?
A)125.3 u B)125.7 u C)126.3 u D)126.7 u

2)What is the most reasonable inference you could make about sulfur (S), which has four stable isotopes and an average atomic mass of 32.06 u?
A). The most common isotope of sulfur has a mass of exactly 32.06 u.
B)Approximately 6% of sulfur atoms have a mass of 32 u.
C)ll of sulfur's isotopes have a mass between 32 u and 33 u.
DThe most common isotope of sulfur is S-32.

Chemistry

2 answers:

lorasvet [960] · Answer 1 · 2026-02-24T14:18:18+03:00

lorasvet [960]9 days ago

6 0

Answer:

Explanation:

0.3(125)+0.7(126)=37.5+88.2=125.7

2. The most prevalent isotope is 32, since the average is very close to this value.

Alekssandra [992] · Answer 2 · 2026-02-24T14:17:30+03:00

Answer:

For question 1: Option B is the correct choice.

For question 2: Option D is the right answer.

Explanation:

Regarding question 1:

The average atomic mass is determined by the total of the masses of each isotope, each weighted by their natural fractional abundance.

The formula used to determine average atomic mass is as follows:

$\text{Average atomic mass }=\sum_{i=1}^n\text{(Atomic mass of an isotopes)}_i\times \text{(Fractional abundance})_i$

The information provided is:

In a sample of 100 atoms of X, 30 have a mass of 125.0 u, and 70 have a mass of 126.0 u. Thus, the fractional abundance of the X-125 isotope is 0.3, while that of the X-126 isotope is 0.7.

For the X-125 isotope:

Mass = 125

Fractional abundance = 0.3

For the X-126 isotope:

Mass = 126

Fractional abundance = 0.7

Substituting the values into the equation yields:

$\text{Average atomic mass }=[(125\times 0.3)+(126\times 0.7)]=125.7u$

Therefore, the answer is Option B.

Regarding question 2:

We know:

The average atomic mass of sulfur = 32.06 u

There are 4 stable isotopes of sulfur: S-32, S-33, S-34, and S-36.

The average atomic mass of sulfur is closer to the mass of the S-32 isotope, indicating that this isotope's relative abundance is greater than that of the others.

The 'S-32' isotope is thus the most abundant isotope of sulfur.

Therefore, the correct response is Option D.