Answer:
Step 1. Calculate the volume of acetic acid
Volume
=
250.0
mL vinegar
×
5 mL acetic acid
100
mL vinegar
=
12 g acetic acid
Step 2. Calculate the mass of acetic acid
The density of acetic acid is 1.05 g/mL.
Mass of acetic acid
=
12
mL acetic acid
×
1.05 g acetic acid
1
mL acetic acid
=
13 g acetic acid
Note: The answer can have only one significant figure because that is all you gave for the percent concentration. However, I calculated the result to two significant figures.