The force ffrom the ground that holds the rock up and prevents her from falling through the gound, unless the ground breaks.
The density of a substance is the quotient we obtain when we divide its mass by the volume. The density is,
density = mass / volume
The mass of carbon tetrachloride is given to be 123.95 grams and that the volume is obtained by subtracting final weight of the completely full-filled with water bottle with the initial weight.
86.55 - 24.25 = 62.3 grams
Since the density of water is 1 grams/ cc. Then, the volume of the bottle is also 62.3 cc. The density is therefore,
density = 123.95 grams/ 62.3 cc = 1.99 g/cc
How the physical world operates.