14524
As quantified by a molybdate assay , the length of the covalently tethered triple helix ( number of POG units ) determines the amount of amorphous silica obtained from silicic acid solution .
 silica, silicic acid
Please list all entity words in the text that fit the category. Output format is "word1, word2". 
Option: Chemical 
Text: {0} 
Answer:
 silica, silicic acid