Which of the following will result in a chemical change?
a. melting ice to obtain water
b. drying wood in a shed
c. burning coal in a furnace
d. evaporating alcohol into vapor

The correct answer is C.

Burning is a chemical change. It's a chemical process that includes oxygen.

All the other options are a change of state: form solid to liquid, or from liquid to  gas (as in the last one).

A chemical change is when it changes the substance itself. It breaks or forms bonds, therefore, you cannot bring it back to the original substance.

Burning coal in a furnace. Because when you burn something, you cannot make it what it used to be. 

Final - C. Burning coal in a furnace. 

Cr(oh)3 -> cr(3+) + 3oh-