Instability of an atoms nucleus can result from an excess of either neutrons or protons . So neutrons and protons .
Sodium (Na) has a +1 charge and Iodine ( I ) has a -1 charge. To create a molecule of sodium iodide the charges will need to balance.
Because the charges on anion and cation are the same; the molecular formula will be NaI
It depends on what type of graph you have. The easiest would be using a H-T diagram. Enthalpy of vaporization is the physical change from liquid to vapor. It occurs at a constant pressure and a constant temperature. As shown in the picture, 1 point is drawn on the subcooled liquid, and another point of the saturated vapor isothermal line. Now, the difference between those two points is the value for the enthalpy of vaporization of water.
Because flammable objects have certain substances, you know that it is a chemical property. For example, cloth is flammable and has a certain substance that MAKES it flammable. This results in a chemical property.