9995
From the perspective of prevention , the spread and prediction of hydrochloric acid ( HCl ) that escaped from the metal - etching chamber during maintenance were studied in this article .
 Chemical: hydrochloric acid; Chemical: HCl
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: hydrochloric acid; Chemical: HCl