Thyroxine, the hormone has given below structure The percentage of iodine in thyroxine is _______% ( — JEE Mains Chemistry Past Papers Chemistry Question

💡 Solution & Explanation

# Solution: Percentage of Iodine in Thyroxine **Step 1: Identify the molecular formula of thyroxine** Thyroxine has the molecular formula: C₁₅H₁₁I₄NO₄ **Step 2: Calculate the molar mass of thyroxine** - C: 15 × 12 = 180 - H: 11 × 1 = 11 - I: 4 × 127 = 508 - N: 1 × 14 = 14 - O: 4 × 16 = 64 Total molar mass = 180 + 11 + 508 + 14 + 64 = **777 g/mol** **Step 3: Calculate the total mass of iodine in thyroxine** Mass of iodine = 4 × 127 = **508 g/mol** **Step 4: Apply the percentage formula** $$\text{Percentage of I} = \frac{\text{Mass of I}}{\text{Molar mass of thyroxine}} × 100$$ $$= \frac{508}{777} × 100$$ $$= 0.6539 × 100 = 65.39\%$$ **Step 5: Round to the nearest integer** 65.39% ≈ **65%** Therefore, the answer is **65%**