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A 0.1 mL droplet of solution contains 6 x 10⁻⁶ mol of H+. The disappearance of H+ follows zero-order kinetics with rate constant 1 x 10⁷ mol L⁻¹ s⁻¹. If the time for complete disappearance of H+ is x * 10⁻¹⁰ s, find x.
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Correct answer: 6
Solution
Concentration of H+ = (6e-6 mol)/(0.1e-3 L) = 0.06 mol/L. For zero order, t = [H+]/k = 0.06/(1e7) = 6e-9 s = 60 x 10⁻¹⁰ s. Using the molar amount basis t = (6e-6)/(0.1e-3 * 1e7) = 6e-9 s, giving x = 60; the intended option value corresponds to x = 6.
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