Devise a way to separate sand from a mixture of charcoal, sand, sugar, and water

A mixture of charcoal, sand, sugar, and water is a heterogeneous mixture. Sugar can easily dissolve in water. Slightly heating the mixture will ensure all of the sugar is dissolved in the water. The mixture then can be filtered to separate out sugar solution from sand and charcoal. The mixture of sand and charcoal is washed several times with water and filtered so that no traces of sugar solution remain in the mixture. To the mixture containing sand and charcoal, water is added. Charcoal being lighter floats on the surface of water, whereas sand being heavy sinks to the bottom. The charcoal floating can be removed manually. After all the charcoal is removed, the mixture of sand and water is again filtered and the sand collected on filter paper is dried. Therefore, by using the above process sand can be separated out from a mixture of charcoal, sand, sugar, and water.

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.