³⁵₁₇Cl and ³⁷₁₇Cl are two isotopes of chlorine. If average atomic weight is 35.5 then ratio of these two isotopes is

Options

(a) 35 : 37
(b) 1 : 3
(c) 3 : 1
(d) 2 : 1

Correct Answer:

3 : 1

Explanation:

Average atomic mass A = (X x a + Y x b) / (X+Y)
35.5 = (35X + 37Y) / (X+Y)
X/Y= 3 / 1