6994
The interference of nitrous acid and nitrous oxides are removed using potassium dichromate .
 Chemical: nitrous acid; Chemical: nitrous oxides; Chemical: potassium dichromate
Given options, please tell me the categories of all the listed entity words.Output format is "type1: word1; type2: word2". 
Option: Chemical 
Text: {0} 
 Entities: nitrous acid, nitrous oxides, potassium dichromate 
Answer:
 Chemical: nitrous acid; Chemical: nitrous oxides; Chemical: potassium dichromate