What is true about exothermic reactions? a. more heat is given off than is put into the reaction. b energy from an outside source is continuously being added. c. the reaction container always feels cold. d. the reactants have more energy than the products.

A. More heat is given off than is put into the reaction

Think of the word "exo" and then think of how the reaction exerts the energy into the reaction. Then "thermic" which can be easily identified with heat

why do the isotopes of a particular element behave differently in nuclear reactions but the same in chemical reactions? chemical reactions involve changes to electrons in an atom; isotopes do not differ in electrons, and so they react the same way during chemical changes.