You have water at 25°C. You dissolve sodium hydroxide, NaOH, in the water and find the temperature increases to 33°C. Which of the following statements is TRUE?

the answer is definitely c.

chemical changes occur when a substance combines with another to form a new substance, called chemical synthesis or, alternatively, chemical decomposition into two or more different substances. these processes are called chemical reactions and, in general, are not reversible except by further chemical reactions. some reactions produce heat and are called exothermic reactions and others may require heat to enable the reaction to occur, which are called endothermic reactions. understanding chemical changes is a major part of the science of chemistry.