7089
Crystalline sodium superoxide ( NaO ( 2 ) ) forms in a one - electron transfer step as a solid discharge product .
 Chemical: sodium superoxide; Chemical: NaO ( 2 )
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: sodium superoxide; Chemical: NaO ( 2 )