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 following psychological tests were performed : four subtests of the Wechsler Adult Intelligence Scale ( similarities , digit span , vocabulary and digit symbol ) , Trail - Making tests A and B , Zung tests ( self - rating anxiety scale and self - rating depression scale ) and two - part memory test battery with immediate and delayed recall .
### Output Text:
The following psychological tests were performed : four subtests of the Wechsler Adult Intelligence Scale ( similarities , digit span , vocabulary and digit symbol ) , Trail - Making tests A and B , Zung tests ( self - rating anxiety scale and self - rating depression scale ) and two - part memory test battery with immediate and delayed recall . 