Question

calculate the average atomic mass for oxygen given the following;
isotope %abundance relative mass mass contribution
o-16 99.7572 15.9949146 amu (1)(15.9949146 amu) = 2 amu
o-17 0.0381 16.9991317 amu (3)(16.9991317 amu) = 4 amu
o-18 0.20514 17.9991611 amu (5)(17.9991611 amu) = 6 amu
7 amu
first we need to convert the % abundance into abundance by dividing by 100.
thus, 99.7572% becomes:
\\(\frac{99.7572}{100}\\) = 8
a. 15.9995 b. 15.9994791 c. 0.0020514 d. 0.000381
e. 0.997572 f. 99.7572. g. 0.03692348 h. 0.0064767
i. 15.956079 j 1.5956079

Explanation:

Step1: Convert %abundance to decimal for O-16

To convert a percentage to a decimal, we divide by 100. So for O - 16 with 99.7572% abundance, we calculate $\frac{99.7572}{100}$.
$\frac{99.7572}{100}=0.997572$

Step2: Calculate mass contribution for O-16

Multiply the decimal abundance (from Step 1) by the relative mass of O - 16. The relative mass is 15.9949146 amu. So we calculate $0.997572\times15.9949146$.
$0.997572\times15.9949146\approx15.9994791$

Step3: Convert %abundance to decimal for O-17

For O - 17 with 0.0381% abundance, convert to decimal by dividing by 100: $\frac{0.0381}{100}$.
$\frac{0.0381}{100}=0.000381$

Step4: Calculate mass contribution for O-17

Multiply the decimal abundance (from Step 3) by the relative mass of O - 17 (16.9991317 amu): $0.000381\times16.9991317$.
$0.000381\times16.9991317\approx0.0064767$

Step5: Convert %abundance to decimal for O-18

For O - 18 with 0.20514% abundance, convert to decimal: $\frac{0.20514}{100}$.
$\frac{0.20514}{100}=0.0020514$

Step6: Calculate mass contribution for O-18

Multiply the decimal abundance (from Step 5) by the relative mass of O - 18 (17.9991611 amu): $0.0020514\times17.9991611$.
$0.0020514\times17.9991611\approx0.03692348$

Step7: Calculate average atomic mass

Sum up the mass contributions of all isotopes. So we add the mass contributions from O - 16, O - 17, and O - 18.
Let $m_1 = 15.9994791$, $m_2=0.0064767$, $m_3 = 0.03692348$. Then the average atomic mass $M=m_1 + m_2+m_3$.
$M=15.9994791+0.0064767 + 0.03692348\approx16.04287928$ (But since the question seems to be about filling the blanks first, let's focus on the blanks:

Blank 1: 0.997572 (from Step 1)
Blank 2: 15.9994791 (from Step 2)
Blank 3: 0.000381 (from Step 3)
Blank 4: 0.0064767 (from Step 4)
Blank 5: 0.0020514 (from Step 5)
Blank 6: 0.03692348 (from Step 6)
Blank 7: Sum of blanks 2,4,6: $15.9994791+0.0064767+0.03692348 = 16.04287928\approx16.04$ (but let's check the options for blank 8: blank 8 is the decimal for O - 16's abundance, which is 0.997572, so option E)

Answer:

For blank 1: 0.997572 (Option E)
For blank 2: 15.9994791 (Option B)
For blank 3: 0.000381 (Option D)
For blank 4: 0.0064767 (Option H)
For blank 5: 0.0020514 (Option C)
For blank 6: 0.03692348 (Option G)
For blank 7: Sum is approximately 16.04 (but if we sum the calculated values: 15.9994791+0.0064767 + 0.03692348 = 16.04287928)
For blank 8: 0.997572 (Option E)