Which of the following is an exothermic reaction?

a.) dissolving sugar in water

b.) melting ice

c.) condensing steam

d.) dissolving ammonium nitrate in water

C.) condensing steam

Explanation:

Exothermic reactions are chemical reaction which energy is released to the environment in the form of heat . The overall energy of the reactant is greater than the energy of the product. The higher in energy of the reactant causes a release of heat to the environment. In exothermic reactions, enthalpy change is  usually negative and is accompanied by the loss of energy in the form of heat or light.

Condensation is the change of water vapor to liquid . The conversion is an exothermic reaction as energy is release to the environment in the form of heat.  The water vapor molecules has higher energy than liquid. The changes of water vapor to liquid causes a loss in energy of the water vapor. As the water vapor loss more energy, heat is been release to the surrounding.

All other reaction are endothermic in which heat is absorb from the environment except for condensation of steam.

people who take vitamin supplements

explanation:

a). in this case, dh> 0 and sd> 0. if t becomes larger, the term "-tds" will become more negative. at some point, it is possible that -dts will be more negative than the dh is positive, and the reaction will become spontaneous. this is probably the correct answer, but you should look at all of the other possibilities and make sure of that.