What is the Atomic Mass of Chlorine? Improve Improve Like Article Like Save Share Report Atomic Mass of Chlorine is . A) 35 B) 35.5 C) 36 D) 34 Answer: Option B) 35.5 is correct. Explanation: Chlorine has two stable isotopes Cl-35 and Cl-37 and the general atomic mass of Chlorine is the average of both isotopes in the ratio of their availability in nature. Now, Cl-35 isotope is 75% of the chlorine gas in the atmosphere. Cl-37 isotope is 25% of the chlorine gas in the atmosphere. Thus, Relative Atomic Mass of Chlorine = 35×75/100 + 37×25/100 = 35.45 amu OR 35.45 u. Last Updated : 21 Dec, 2023 Like Article Save Article Previous Nickel - Occurrence, Properties, Symbol, Uses, Facts Next What is the Atomic Mass of Potassium? Share your thoughts in the comments Add Your Comment Please Login to comment...