24408
Hydrogen sulfide ( H2S ) , known as an important cellular signaling molecule , plays critical roles in many physiological and / or pathological processes .
 Chemical: Hydrogen sulfide; Chemical: H2S
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 sulfide; Chemical: H2S