The first answer is right in that you should use water. However, this answer does not give all the steps needed to find the density of the object.

If you put the object in water, the amount that the water level goes up is the volume of the object. So, in the example given above, the volume of the object is 6 ml.

However, to find the density, you must also know the mass of the object because **mass = density*volume.**

So, find the volume using the water test. Then find the mass. Then use the formula above.

Off the top of my head, the water displacement method might be the best way to measure the density of this object. In this method, the ability of the object to float or sink is of critical importance. When you place the object in water, there should be a rise in the water level because the object impacts the water level causing it to increase. The difference between both levels of water is the density of the object. For example, if you had 20 ml of water as a starting point, and then you placed the object in water and the level rose to 26 ml, the difference between both levels (26-20) is 6 ml. This means that the density would be reflective of the change in water levels.

I am adding on to this because I realized that part of my original answer did not come through. The density as indicated above would be the volume present, and setting it up as mass/ volume would allow you to obtain the density. Sorry about this mixup. I accept full responsibility on it.