Which of the following is true concerning redox reactions? a. double-replacement reactions are always redox reactions. b. single-replacement reactions may be redox reactions. c. acid-base reactions are always redox reactions. d. all of the above

B. Single-replacement reactions may be redox reactions.

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answer: enthalpy

explanation:

for a exothermic reaction, the energy is released i.e. the energy of the products is lower than the energy of the reactants.

= enthaply

= energy of products

= energy of reactants

as , thus comes out to be negative. negative value of enthalpy shows that the reaction is exothermic.