Look at the four chemical reactions. Reaction 1: 2H2 + O2 → 2H2O Reaction 2: 2NaCl → 2Na + Cl2 Reaction 3: CaO + H2O → Ca(OH)2 Reaction 4: 4Fe + 3O2 → 2Fe2O3 Which statement identifies the reaction that is different from the rest and explains correctly why it is different? (1 point) Reaction 2, because a single reactant is decomposed Reaction 1, because two reactants have decomposed Reaction 2, because a single ion is replaced in a compound Reaction 1, because two ions have interchanged their positions

Exothermic,  physical change after it is already baked

Answerthis solution will not form a precipitateexplanationsolubility equilbrium:         pbf₂(s)  ⇄ pb²⁺(aq) + 2 f⁻(aq)the solubility product expression is    (we exclude solids from the equilibrium expression).now suppose we have the trial ion product q, which we can define as    then, we can interpret  q as the product of the concentration of the ions that we have and ksp as the product of the ion concentrations that are needed to form a saturated solution.if q > ksp, then that implies that there will be a surplus of ions that exceed the amount that is required to form a saturated solution. a precipitate will then form (the precipitate continually  forms until the surplus ions are removed and q is decreased to ksp's value).if q = ksp, the saturated solution that forms is barely saturated and the precipitate will be minimal.if q < ksp, then the ion concentration will not be enough to form a saturated solution (so no precipitate).using our information, we calculate the trial ion product:     since q = 2.7  × 10⁻⁸ < ksp =  4  ×  10⁻⁸, a precipitate will not form.

"electrical energy" transforms to "thermal energy".hope my answer has you : )