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: Also , 7 of 12 drivers appeared to adjust their driving behaviour by reducing their speed on the driving simulator , leading to improved steering accuracy .
### Output Text:
Also , 7 of 12 drivers appeared to adjust their driving behaviour by reducing their speed on the driving simulator , leading to improved steering accuracy . 