Avogadro's number is a constant that define the number of particles (Such as atoms, molecules, electrons, ions) that you have in 1 mole. That means in 1 mole you have 6.022x10²³ of the particle in question.
If you have 6.578x10²³ atoms of Mg -and 1 mole of Mg contains 6.022x10²³ atoms of Mg-:
6.578x10²³ atoms of Mg × (1 mole Mg / 6.022x10²³ atoms of Mg) =
Exothermic is a chemical reaction in which heat is released. Lighting a candle is an example of an exothermic because the flame is the heat being released.
