34766
Of these , the most commonly used in the laboratory are Cl ( " t " = 3.0 × 10 " y ) and Cl ( " t " = 37.2 " min ) , which may be produced from the neutron activation of natural chlorine .
 Cl
Please list all entity words in the text that fit the category. Output format is "word1, word2". 
Option: location, person, organization 
Text: {0} 
Answer:
 Cl