6082
Size - dependent nanostructural transformations occurring during the H ( 2 ) - mediated reduction of hollow and porous NiO nanoparticles were investigated for controlled nanoparticle sizes of ~ 10 to 100 nm .
 Chemical: H ( 2 ); Chemical: NiO
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 ( 2 ), NiO 
Answer:
 Chemical: H ( 2 ); Chemical: NiO