Answer: Catalyst
Explanation: it speeds it up lol but basically the catalyst helps speed up the chemical reaction by reducing the activation energy or changing the reaction machenism/
Oxygen for complete combustion
<span>Tf is the freezing point of the solution(the solvent plus solute).
T*f is the freezing point of the pure solvent(without solute)
i is the van't Hoff factor.It is approximately the number of particles in solution that are made for each particle of the solute that is placed into solution.Therefore, for nonelectrolytes, i = 1.
Kf is the freezing point depression constant.For water, Kf = 1.86 Degree C/m, or 1.86 Degree C.kg/mol.
Tf is -1.58 Degree C</span>
Magnesium. You can count the electrons in each level and because the number of electrons is the same with protons you have the atomic number based of which you can get the element in the periodic table