Here's the definition of 'Density'. You should memorize it.
We used it to answer #5 a few hours ago.
Density = (number of grams) divided by (number of mL) .
#6). Number of grams = 65.14
Volume = 35.4 mL
Just write these numbers in the definition, then divide,
and you'll have the density.
#7). Here, they gave you the density and the volume, and
they want you to find the mass.
Not a problem. Just write the numbers you know into
the definition again:
Density = (number of grams) divided by (the volume)
0.8765 = (number of grams) divided by (250 mL)
Multiply each side of this equation by 250 mL, and then it says
(0.8765) x (250 mL) = number of grams
Run this through your calculator, and you'll have the answer.