Density
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Density is the ratio of a substance's mass to its volume. The symbol most often used for density is ρ, although the Latin letter D can also be used: ρ = m V, where ρ is the density, m is the mass, and
A test tube holding four non-miscible colored liquids with different densities
One-troy-ounce (480 gr; 31 g) samples of germanium, iron, aluminium, rhenium and osmium. The differences in size are due to differences in density.
Plutonium
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Plutonium is a chemical element; it has symbol Pu and atomic number 94. It is a silvery-gray actinide metal that tarnishes when exposed to air, and forms a dull coating when oxidized. The element norm
A sample of plutonium metal, shaped like a ring to prevent nuclear criticality
Various oxidation states of plutonium in solution
Plutonium pyrophoricity can cause it to look like a glowing ember under certain conditions.
Twenty micrograms of pure plutonium hydroxide