Question

Question #228b4

Answer 1

`"100 cm"^3`

Explanation:

The thing to remember about the density of a substance is that it's supposed to tell you the mass of exactly `1` unit of volume of that substance.

In your case, the boulder is said to have a density of `"8 g/"color(blue)("cm"^(3))`, which means that `color(blue)("1 cm"^3)` of this boulder has a mass of `"8 g"`. In other words, every time you have a mass of `"8 g"` of this boulder, the sample will occupy `color(blue)("1 cm"^3)`.

You can thus use the density of the boulder as a conversion factor to calculate the volume of the `"800-g"` sample

`800 color(red)(cancel(color(black)("g"))) * overbrace(color(blue)("1 cm"^3)/(8color(red)(cancel(color(black)("g")))))^("the given density = 8 g/"color(blue)("cm"^3)) = color(darkgreen)(ul(color(black)("100 cm"^3)))`

The answer is rounded to one significant figure.

So remember, when a problem provides you with the density of the substance, it's essentially giving you the mass of exactly `1` unit of volume of that substance.