Boron occurs in two varieties, namely, ${ }^{10} \mathrm{~B}$ (atomic mass: $10.01 \mathrm{amu}$ ) and ${ }^{11} \mathrm{~B}$ (atomic mass: $11.01 \mathrm{amu}$). The atomic mass of naturally occurring element is reported as $10.82 \mathrm{amu}$. The per cent of ${ }^{10} \mathrm{~B}$ in this…

Question

Boron occurs in two varieties, namely, ${ }^{10} \mathrm{~B}$ (atomic mass: $10.01 \mathrm{amu}$ ) and ${ }^{11} \mathrm{~B}$ (atomic mass: $11.01 \mathrm{amu}$). The atomic mass of naturally occurring element is reported as $10.82 \mathrm{amu}$. The per cent of ${ }^{10} \mathrm{~B}$ in this naturally occurring boron is

Aicharya · Accepted Answer

If $x$ is the fraction of ${ }^{10} \mathrm{~B}$, we have $\quad x(10.01 \mathrm{amu})+(1-x)(11.01 \mathrm{amu})=10.82 \mathrm{amu}$ This gives $x=0.19$. Hence, percentage is $19 \%$.

Boron occurs in two varieties, namely, ${ }^{10} \mathrm{~B}$ (atomic mass: $10.01 \mathrm{amu}$ ) and ${…

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