Thyroxine, the hormone has given below structure The percentage of iodine in thyroxine is ____ $\%$.…

Thyroxine, the hormone has given below structure

The percentage of iodine in thyroxine is ____ $\%$. (nearest integer)
(Given molar mass in $\mathrm{g} \mathrm{mol}^{-1} \mathrm{C}: 12. \mathrm{H}: 1, \mathrm{O}: 16$, $\mathrm{N}: 14, \mathrm{I}: 127)$

Solution

$\rightarrow$ Molecular formula of Thyroxine $\Rightarrow$ $\mathrm{C}_{15} \mathrm{H}_{11} \mathrm{O}_4 \mathrm{NI}_4$
$\rightarrow$ Molecular mass of Thyroxine -
$\begin{aligned} & \mathrm{C} \rightarrow 15 \times 12=180 \\ & \mathrm{H} \rightarrow 11 \times 1=11 \\ & \mathrm{O} \rightarrow 16 \times 4=64 \\ & \mathrm{~N} \rightarrow 14 \times 1=14 \\ & \mathrm{I} \rightarrow 127 \times 4=508\end{aligned}$
$\rightarrow$ Molecular mass of Thyroxine $\Rightarrow 777$
$\begin{aligned}& \rightarrow \% \text { of Iodine }=\frac{508}{777} \times 100 \\& =65.38 \%\end{aligned}$
Nearest integer $=65$

Asked in: JEE Main 2025 (07 Apr Shift 1)

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