3. When the zinc is added to the solution copper gains electrons and becomes a solid while the zinc loses electrons and becomes soluble in water. What type of reaction is this?

the correct answer is:

a. formation of precipitation

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.