Question

calculate the relative atomic mass of these isotopes *
oxygen-16 percent abundance 99%
oxygen-17 percent abundance 0.02%
oxygen-18 percent abundance 0.08%

Explanation:

Step1: Convert percentages to decimals

$99\% = 0.99$, $0.02\%=0.0002$, $0.08\% = 0.0008$

Step2: Multiply mass - number by abundance for each isotope

Oxygen - 16: $16\times0.99 = 15.84$
Oxygen - 17: $17\times0.0002=0.0034$
Oxygen - 18: $18\times0.0008 = 0.0144$

Step3: Sum the results

$15.84+0.0034 + 0.0144=15.8578$

Answer:

$15.8578$