Concentrated `H_(2)SO_(4)` is added to each of the five test tubes containing (i) NaBr, (ii) sugar, (iii) sulphur powder, (iv) KCl and (v) copper turnings. The test tubes are then heated. Identify in which of the test tubes the following changes will be observed. The observations are: formation of a black substance.
Support your answer with the help of a chemical equation in this case.

Explanation

When conc. `H_(2)SO_(4)` is heated with sugar taken in test tube (ii), sugar undergoes dehydration to form black sugar charcoal.
`underset("sugar")(C_(12)H_(22)O_(11))underset(Delta)overset("conc." H_(2)SO_(4))tounderset("(black sugar charcoal)")(11H_(2)O+12C)`