In the sentence extracted from biomedical literature, identify all the chemical entities. The required answer format is the same sentence with HTML <span> tags to mark up specific entities. 
### Entity Markup Guides:
Use <span class="chemical"> to denote a chemical.

### Input Text: Participants were also assessed with the " Eyes task " to investigate their ability to recognize more complex emotional states and the Symptom CheckList - 90 - Revised to measure psychopathology .
### Output Text:
Participants were also assessed with the " Eyes task " to investigate their ability to recognize more complex emotional states and the Symptom CheckList - 90 - Revised to measure psychopathology . 