Mercury is a fascinating element. Of all the metal elements, mercury is the only one that is liquid at room temperature; the rest are all solid. However, mercury is also capable of existing in the solid state.

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.