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.