How can the particle theory of matter explain how solutes dissolve in solvent?

Which of the following is always a reactant in a combustion reaction? oxygen nitrogen hydrogen carbon

What is the most common reason for matter changing its state?

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