Identify which of the following are oxidation-reduction reactions. If a reaction is a redox reaction, name the element oxidized and the element reduced. a. Mg(s) + Br2(l) → MgBr2(s) b. H2CO3(aq) → H2O(l) + CO2(g) c. CaCO3(s) + 2HCl(aq) → CaCl2(aq) + H2O(l) + CO2(g) d. CuO(s) + H2(g) → Cu(s) + H2O(l) e. Li(s) + H2O(l) → LiOH(aq) + H2(g) f. NaCl(aq) + AgNO3(aq) → NaNO3(aq) + AgCl(s) g. HgO(s) → Hg(l) + O2(g) h. P4(s) + O2(g) → P4O10(s) i. C3H8(g) + O2(g) → CO2(g) + H2O(g) j. Al(s) + HCl(aq) → AlCl3(aq) + H2(g)

the law of conservation of mass states that in a chemical reaction, the total mass of reactants is equal to the total mass of products. because atoms are only rearranged in a chemical reaction, there must be the same number of sodium atoms and chlorine atoms in both the reactants and products

"among the transition metal elements, manganese and zinc have a slight lowering of electronegativities. the reason behind this is that the nuclear charges of these elements are slightly weaker than the other transition metal elements due to the way their valence electrons are filled up. both manganese and zinc have their valence electrons filled up to the 4th shell with 1 pair of electrons (4s2) completely occupying it. although the electrons in the 3rd shell (3d) are yet to be paired since the outer most shell is filled up, the ability of the nucleus to attract electrons is lessened. hence,   the electronegativity (or the ability to attract electrons) is lessened."