What is the Atomic Mass of Chlorine? Last Updated : 21 Dec, 2023 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. Like Article Suggest improvement Previous Packing Efficiency of Unit Cell Next What is the Atomic Mass of Potassium? Share your thoughts in the comments Add Your Comment Please Login to comment...