What happens to the particles in a solid as it is heated? The particles move faster and spread further apart.
The particles move at the same speed and stay the same distance apart.
The particles move more slowly and move closer together.
The particles move faster and move closer together.

The particles move faster and spread further apart

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.