Subject: Inorganic Chemistry · Chapter: D Block · Topic: D Block – General · Exam: JAM 2005-2022 · Marks: 2 · Difficulty: Easy
4(a) A solution of metal ion $\left(\mathrm{M}^{2+}\right)$ when treated with $\mathrm{H}_{2} \mathrm{S}$ gas gives a black precipitate A . Precipitate A dissolved in hot concentrated nitric acid to give B along with elemental sulfur. The metal ion soluion also gives a white precipitate C with an excess of KI. Write the chemical formulae of A, B and C
(b)Why are potassium permanganate solutions unstable in the presence of $\mathrm{Mn}^{2+}$ ions? In the quantitative estima tion of iron present in iron ores dissolved in dilute HCl , titrations with dichromate are preferred over titrations with permanganate. Rationalise.