The answer is True: Any substance can be known by measuring it's density and comparing that density with other substances we already know, so we can give an idea of which group of elements that substance belongs to. It is good to remember that Density (D) is obtained by dividing the mass (M) between volume (V).
For example, when encountering an unknown substance, we can know it's volume by inserting the object into a graduated cylinder, with a known amount of water, and measuring the new volume with the substance in the water; Thus, the mass is divided between the volume, and having then obtained the results, we look for the density of known elements and at the end we can know to which group of elements belongs.
