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: ( + / - ) - PG - 9 ( 10 - 40 mg kg - 1 i . p . ) was able to prevent amnesia induced by scopolamine ( 1 mg kg - 1 i . p . ) and dicyclomine ( 2 mg kg - 1 i . p . ) in the mouse passive - avoidance test .
### Output Text:
( + / - ) - <span class="chemical">PG - 9</span> ( 10 - 40 mg kg - 1 i . p . ) was able to prevent amnesia induced by <span class="chemical">scopolamine</span> ( 1 mg kg - 1 i . p . ) and <span class="chemical">dicyclomine</span> ( 2 mg kg - 1 i . p . ) in the mouse passive - avoidance test . 