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: Newborn rats were given terbutaline ( 10 mg / kg ) daily on postnatal days ( PN ) 2 to 5 or PN 11 to 14 and examined 24 h after the last dose and at PN 30 .
### Output Text:
Newborn rats were given <span class="chemical">terbutaline</span> ( 10 mg / kg ) daily on postnatal days ( PN ) 2 to 5 or PN 11 to 14 and examined 24 h after the last dose and at PN 30 . 