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← JEE Main 2017 · 8 Apr · Shift 1
ChemistrySingle correct+4 / -1Question 32 of 90

JEE Main 2017 · 8 Apr · Shift 1, Chemistry question 32

Excess of NaOH (aq) was added to 100 mL of FeClX3\ce{FeCl3} (aq) resulting into 2.14 g of Fe(OH)X3\ce{Fe(OH)3}. The molarity of FeClX3\ce{FeCl3} (aq) is :

(Given molar mass of Fe = 56 g mol−1^{-1} and molar mass of Cl = 35.5 g mol−1^{-1})

Choose one option
Answer and worked solution

Official answer: A

Fe(OH)X3\ce{Fe(OH)3} has molar mass 107 g mol⁻¹, so 2.14107=0.02\dfrac{2.14}{107}=0.02 mol, which equals the moles of FeClX3\ce{FeCl3}. In 0.1 L that is 0.2 M.