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: The number of patients who developed ARF on the second day after the injection in the first group was five ( 25 % ) , in the second group was six ( 30 % ) and the third group was five ( 25 % ) ( p > 0 . 05 ) .
### Output Text:
The number of patients who developed ARF on the second day after the injection in the first group was five ( 25 % ) , in the second group was six ( 30 % ) and the third group was five ( 25 % ) ( p > 0 . 05 ) . 