The average molar mass of chlorine is $35.5\ \mathrm{g\,mol^{-1}}$. The ratio of $^{35}\mathrm{Cl}$ to $^{37}\mathrm{Cl}$ in naturally occurring chlorine is close to :

JEE Main 2020 · ChemistryMultiple choiceSingle correctEasyCalculation

JEE Main 6 September 2020, Shift 2, Chemistry Q40

Question 40 of 75 in this shift, Chemistry question 15 of 25.

The average molar mass of chlorine is

35.5\ \mathrm{g\,mol^{-1}}

. The ratio of

^{35}\mathrm{Cl}

^{37}\mathrm{Cl}

in naturally occurring chlorine is close to :

(1)1 : 1
(2)2 : 1
(3)3 : 1Official answer
(4)4 : 1

Official answer

Option 3

NTA final key (Sep 2020).

Chapter: Some Basic Concepts of Chemistry
Topic: Mole Concept
Idea tested: Average Atomic Mass from Isotopes

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Question text from the official JEE Main paper published by NTA; answer from the final answer key. Chapter, topic and idea tags, difficulty and skill are Lumi’s. Lumi analyses 42 of the 174 JEE Main shifts held from 2017 to 2026.