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: All compounds at 0 . 1 - 1 mg / kg p . o . significantly improved the amnesia induced by scopolamine ( 0 . 5 mg / kg s . c . ) in rats performing a passive avoidance task .
### Output Text:
All compounds at 0 . 1 - 1 mg / kg p . o . significantly improved the amnesia induced by <span class="chemical">scopolamine</span> ( 0 . 5 mg / kg s . c . ) in rats performing a passive avoidance task . 