Answer
Please see the work below.
Work Step by Step
We know that
$V_i=\frac{M_fV_f}{M_i}$
We plug in the known values to obtain:
$V_i=\frac{0.12\times 1000}{15.8}=7.594mL$
You can help us out by revising, improving and updating this answer.
Update this answerAfter you claim an answer you’ll have 24 hours to send in a draft. An editor will review the submission and either publish your submission or provide feedback.