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: Nefiracetam is a novel pyrrolidone derivative which attenuates scopolamine - induced learning and post - training consolidation deficits .
### Output Text:
<span class="chemical">Nefiracetam</span> is a novel <span class="chemical">pyrrolidone</span> derivative which attenuates <span class="chemical">scopolamine</span> - induced learning and post - training consolidation deficits . 