Number the steps for balancing equations:
Use coefficients to increase the atoms on each side.
Check to make sure you have the same number of each type of atom on each side.
Count the atoms on each side,
Identify the atoms on each side.
Intro

answer: the rock sample is a sedimentary rock.

explanation:

it is given that:

mass of rock sample, m = 2.7 g

volume of rock sample,

so, density of rock sample will be

since, the density of rock sample is . hence, the rock sample is a sedimentary rock, whose densities varies between .

3. dark matter

empty space could also be a simple vacuum