Example 2 (organic) answer

An orange to green colour change on heating with sodium dichromate shows that oxidation has taken place

The reaction with the phosphorus pentachloride (video) shows that the molecule contains an OH group. The ready oxidation with acidified sodium dichromate (video) indicates a primary or secondary alcohol.

The boiling point then allows us to identify the particular alcohol involved. From the data book, the nearest boiling point to the one which was measured is ethanol at 78 ºC.

Conclusion: the unknown organic compound is ethanol.