A runner takes 60 seconds to run a lap around the track. What is its frequency

Avariable that is not being directly tested during an experiment should be

Air can be considered a mixture. which statement does not explain why?

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