5 gm/cc
25/1000 = 0.025 gram per cubic cm
Density = (mass) / (volume) = 27/10 = 2.7 gm/cm3 .
Density = Mass/Volume, with this equation, if two things are given the third can easily be calculated. In your question, you was volume when density and mass are given. So Volume = Mass/Density
You can measure the volume by filling a container (the best option would be an accurate measuring cilinder) with water. Note how much water is in the container, now immerse the object you want to measure in the water and once more note how much water is in the container. The difference between your second measurement and the first is the total volume of the object. Another way would be to weigh the object and then calculate its volume via its density Density=mass/volume so volume=mass/density. This method only works if your know the density of the object. A third way would be to simply measure the dimensions of the object and mathematically calculate the volume (e.g. a cube would be length*width*height).
Not enough information. Density = mass / volume. If you know TWO of those numbers, you can calculate the third.
Volume
Not necessarily. a cube of 1x1x1 of solid gold weights over 19 times than a 1x1x1 cube of water. It takes 2 of the factors, volume, weight, and density to determine the third.
You need to know two of them - either from your own or other people's measurements. The third can then be determined using Density = Mass/Volume
Because the volume of a cube is the third power of the length of its side.
The third power.
0.5g is not a density. Density has units of mass/volume. Even if you assume that that means something like 0.5g/cm3, there isn't enough information. You can use the relationship: mass = volume x density If you know any two of these, you can calculate the third one.
Because, to find the volume of a cube, you raise the length of the side to the third power: if the side of a cube is 2, the volume is 2^3 or 8.