Which pair of elements will form an ionic bond? a. Potassium and Oxygen
b. Iron and Barium
C. Sulfur and Nitrogen
d. Calcium and Silicon

Which best describes the activation energy of a chemical reaction? a. the combined energy of all the reactants b. the amount of energy required for a reaction to occur c. the difference in energy between products and reactants d. the potential energy stored in the bonds of reactants and products