21247
The predominant gauche structure maintains an intramolecular hydrogen bond in carbon tetrachloride ( HB structure ) , whereas HB and NoHB gauche conformers appear in nearly the same fraction in aqueous solution .
 hydrogen, carbon tetrachloride
Please list all entity words in the text that fit the category. Output format is "word1, word2". 
Option: Chemical 
Text: {0} 
Answer:
 hydrogen, carbon tetrachloride