A student takes four samples of a white crystalline solid and places each in a well plate. On top of each sample, she carefully places 20 drops of mystery liquids A, B, C and D. Her results for each well are:


The solid dissolves quickly in liquid A.
The solid remains unchanged with the addition of liquid B.
The white solid remains, but dissolves very slowly in liquid C.
When liquid D is added, fizzing occurs and the well becomes warmer.

In which well does a chemical change occur?