20753
H - H and Si - H Bond Addition to Fe = NNR2 Intermediates Derived from N2 .
 Chemical: H - H; Chemical: Si - H; Chemical: Fe = NNR2; Chemical: N2
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: H - H, Si - H, Fe = NNR2, N2 
Answer:
 Chemical: H - H; Chemical: Si - H; Chemical: Fe = NNR2; Chemical: N2