On a graph of temperature vs. time, it shows pure substances exhibit a sharp boiling point and a sharp melting point as a horizontal flat line wherein the temperature does not change over time up until all the pure substances boiled or melted. The temperature stays stable at 160°C between 4 minutes and 11 minutes. This horizontal flat line part of the graph is normal of a pure substance. The melting point of a solid substance is usually used to specified if the substance is pure. Likewise, the boiling point of a "liquid" substance can be used to specify if the substance is pure as well.
Density and solubility are similar because they both involve water, but they are different because density involves dissolving a material and solubility involves floating or sinking a material.
Each "human body cell" has 46 chromosomes. But human sex cells have 23 unpaired chromosomes in each cell. Sex cells are created by a special type of cell division, Meiosis.
