27651
Because permeabilities of H2 , N2 , O2 , and CO2 gases through the membranes primarily depended on their kinetic diameters , the gas permeation behavior of the various TOCNs can be explained in terms of a diffusion mechanism .
 Chemical: H2; Chemical: N2; Chemical: O2; Chemical: CO2
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: H2; Chemical: N2; Chemical: O2; Chemical: CO2