Choose the correct statements about iodometric and iodimetric titrations.

AIn iodometry, an oxidising agent liberates iodine from excess KI and the iodine is titrated with thiosulfate
BIn iodometry, starch is added at the very beginning so that the blue colour guides the titration throughout
CIn iodimetry, a standard iodine solution is used directly to titrate a reducing agent
DThe equivalent mass of $Na X_{2} S X_{2} O X_{3}$ in its reaction with iodine equals its molar mass

Answer: A, C, D

Iodometry is indirect: oxidant + I

^{-}

gives

I X_{2}

, then thiosulfate (true). Starch is added near the end point (pale yellow stage), because a large amount of iodine forms an adsorbed complex that is slow to decolourise (false). Iodimetry uses direct titration with

I X_{2}

(true). Thiosulfate has n = 1, so its equivalent mass equals its molar mass (true).

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Choose the correct statements about iodometric and iodimetric titrations.

Answer: A, C, D

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