Which compound is more soluble in water

Rules of thumb water solubility

Hi,

I will soon be writing an exam in chemistry. Our teacher gave us a few sample assignments; but I just don't understand this and I urgently need help with it.

Task 3: Sorbitol is used as a sweetener. a) why is the fabric solid? b) Create the reaction equation for the combustion of sorbitol.

Task 4: You have 2 bottles with the labels peeled off. One bottle has 1-butanol and the other has 2-butanol. a) draw the two alcohols (I can do the task, but I don't know how to set the oxidation numbers). b) Which alcohol is in which bottle? Explain using the reaction equation (with partial equations for Red. And Ox.) How you can assign the alcohols.

There was also a task in which I was given 3 substances (heptane, dean 1-ol and ethane 1,2 diol) and was supposed to sort them according to their solubility. I would sort the substances like this: ethane 1,2 diol (the most soluble), decan-1-ol, heptane. I would sort them this way because the substances with the most OH groups are the most soluble. If 2 substances have the same number of OH groups, the one with the fewer carbons is the more soluble. (This is about the water solubility). Is my order and reasoning correct?

Thank you for all helpful answers, I am really desperate with these tasks.