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Chemistry · Some Basic Concepts of Chemistry
हिन्दीBoron occurs in nature as two isotopes: \( ^{10}\text{B} \) (isotopic mass = \( 10.01\text{ u} \)) and \( ^{11}\text{B} \) (isotopic mass = \( 11.01\text{ u} \)). If the average atomic mass of boron is \( 10.81\text{ u} \), the percentage relative abundance of the lighter isotope \( ^{10}\text{B} \) is:
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Correct answer · Option B
\( 20\% \)
Explanation
Let \( x \) be the fraction of \( ^{10}\text{B} \). Then \( 10.01x + 11.01(1 - x) = 10.81 \implies -x = -0.20 \implies x = 0.20 \), so the abundance is \( 20\% \).
