Task: Named Entity Recognition
Input (English): Chemical reactions break down the bonds holding the rocks together. The rocks fall apart. They form smaller and smaller pieces. Oxidation takes place when oxygen combines with other elements in rocks. They form new types of rocks. The new substance is softer. Carbonation takes place when carbon dioxide reactions with certain types of rocks. A solution is formed that can easily be carried away by water. 
Output (English): rocks ; smaller pieces ,oxygen ,new types of rocks ; new substance ; certain types of rocks