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: In 2 separate sessions , a single dose of scopolamine ( 0 . 5 mg , intravenously ) or placebo was administered , and the effects on word recall were measured using the Buschke Selective Reminding Test over 2 hours .
### Output Text:
In 2 separate sessions , a single dose of <span class="chemical">scopolamine</span> ( 0 . 5 mg , intravenously ) or placebo was administered , and the effects on word recall were measured using the Buschke Selective Reminding Test over 2 hours . 