Nuclear Chemistry and RadioactivityhardMCQ SINGLE⭐ Must-Do

The fractional atomic weight of natural Chlorine is approximately . This arises because Chlorine funNuclear Chemistry and Radioactivity Chemistry Question

Question

The fractional atomic weight of natural Chlorine is approximately $35.5$. This arises because Chlorine fundamentally exists as a mixture of two stable isotopes, ${}^{35}Cl$ and ${}^{37}Cl$. What is the molar abundance ratio of ${}^{35}Cl$ to ${}^{37}Cl$ in nature?

Answer: C

💡 Solution & Explanation

Let the abundance of ${}^{37}Cl$ be $y$, and ${}^{35}Cl$ be $(1-y)$. The average mass $= 35(1-y) + 37y = 35.5$. Solving gives $y = 0.25$ (25%) and $1-y = 0.75$ (75%). The ratio of 35 to 37 is $75:25$ or $3:1$.

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