[ocojam]

 Iron tablets were crushed, added to dilute sulfuric acid and then filtered. The filtrate and washings were added to a volumetric flask and water was added to make it up to 250cm3. Then the solution was titrated with potassium managanate. The iron tablets contained insoluble filler.
 1) Why was it important to remove the insoluble filler when making up the solution?
Not sure on this?

2) It is suspected that some of the iron(II) in the tablets has changed to iron (III). could potassium hexacyanoferrate(III) be used to confirm the suspicion?
 It goes dark blue with both iron(II) and iron(III) right? So it can't be used?

[AWK]

Search for tablets' content. Probably reductor may be added (eg vitamin C). Other organic additives react with permanganate.