21553
Moreover , a minor contribution relative to hydrogen is found in the CX3O2 + IO ( X = H and F ) reactions .
 Chemical: hydrogen; Chemical: CX3O2; Chemical: IO; Chemical: H; Chemical: F
Please list all entity words in the text that fit the category.Output format is "type1: word1; type2: word2". 
Option: Chemical 
Text: {0} 
Answer:
 Chemical: hydrogen; Chemical: CX3O2; Chemical: IO; Chemical: H; Chemical: F