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← JEE Main 2022 · 25 Jun · Shift 2
ChemistryInteger+4 / -1Question 85 of 90

JEE Main 2022 · 25 Jun · Shift 2, Chemistry question 85

A solution of Fe2(SO4)3\mathrm{Fe_2(SO_4)_3} is electrolyzed for 'x' min with a current of 1.5 A to deposit 0.3482 g of Fe. The value of x is ______. [nearest integer]

Given : 1 F = 96500 C mol−1^{-1}

Atomic mass of Fe = 56 g mol−1^{-1}

Answer and worked solution

Official answer: 20

Charge. Fe3++3e−→Fe\mathrm{Fe^{3+}+3e^-\rightarrow Fe}: 0.348256×3×96500≈1800\dfrac{0.3482}{56}\times3\times96500\approx1800 C.

Time. t=18001.5=1200t=\dfrac{1800}{1.5}=1200 s =20=20 min.

Answer: 20