Question

the four naturally occurring isotopes of sulfur are s - 32, s - 33, s - 34, and s - 36. the table below shows the atomic mass and percent natural abundance for these isotopes. the weighted average atomic mass of sulfur would be closest to which isotope? click on the isotope to indicate your answer choice.
naturally occurring isotopes of sulfur

isotope	atomic mass (u)	natural abundance (%)
s - 33	32.971	0.75
s - 34	33.968	4.25
s - 36	35.967	0.01

Explanation:

Step1: Recall weighted - average formula

The formula for the weighted - average atomic mass ($A_{avg}$) of an element with isotopes $i$ having atomic masses $m_i$ and natural abundances $p_i$ (in decimal form) is $A_{avg}=\sum_{i}m_i\times p_i$.

Step2: Convert percentages to decimals

$p_{32}=0.9499$, $p_{33}=0.0075$, $p_{34}=0.0425$, $p_{36}=0.0001$.

Step3: Calculate the weighted - average atomic mass

$A_{avg}=31.972\times0.9499 + 32.971\times0.0075+33.968\times0.0425 + 35.967\times0.0001$
$A_{avg}=31.972\times0.9499=30.3802028$
$32.971\times0.0075 = 0.2472825$
$33.968\times0.0425=1.44364$
$35.967\times0.0001 = 0.0035967$
$A_{avg}=30.3802028+0.2472825 + 1.44364+0.0035967=32.074722$

Answer:

S - 32