The following chemical test are using to identify inorganic and organic(alcohol, ketone, alkene, carbohydrates) compunds. Explain why each color change, precipatate formation, gas evolution, occurred

1.Solubily in water and hexane
2.Density for a liquid and a solid (procedure and calculations)
3. Chromic acid test (CrO42-)
4. Potassium permanganate Test (KMnO4)
5. Test with Iodine
6. Test with Benedict's Solution
7. Tests for anions and cations

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Basically, you're being asked what each test does.

I kind of know that, but I don't know how to start.

#1. Consider the first test. Most nonpolar hydrocarbons are soluble in hexane but insoluble in water. Remember the adage, "oil and water don't mix"? On the other hand, alcohols, especially short-chain alcohols, are soluble in water and hexane. Inorganic salts are (typically) very soluble in water but insoluble in hexane.

#2. The density of most organic compounds is near or below 1.0 g/cc. Water is, of course, 1 gram/cc (nominally). Many inorganic compounds have a much higher density.

#3. Chromic acid is an oxidizing agent. Some materials can be oxidized; others can't.

#4. Potassium permanganate is also an oxidizing agent, similar to #3. The differences in how they react and oxidize other compounds can be used to indicate what compound is present. You can do research into the reactions of chromic acid and potassium permanganate to figure out what the differences are and what it can tell you about the compound you're trying to identify.

#5. See #3 & #4. Iodine often reacts across double bonds.

#6. Benedict's reagent - Wikipedia, the free encyclopedia

#7. What are the tests for anions and cations? What does this tell you? The presence of anions and cations would usually point to inorganic compounds. Carboxylic acids and other organic acids with "acidic" hydrogen atoms, might show the presence of anions (and hydrogen ions), but in general, other organic compounds would not.

This is juist a starting point. You should look up what each reaction is expected to do. In both inorganic and organic chemistry, there are usually flow charts containing rules to follow to identify compounds. For example, in qualitative inorganic analysis, you start in acid solution and usually bubble H2S into that solution. Certain sulfides will precipitate in acid solution; others won't. Eventually, you get into basic solution to precipitate those materials. That's the idea behind all of this.