Question

A red solid is insoluble in water. However it becomes soluble
if some KI is added to water. Heating the red solid in a test
tube results in liberation of some violet coloured fumes and
droplets of a metal appear on the cooler parts of the test
tube. The red solid is
(a) HgI₂ (b) HgO
(c) Pb₃O₄ (d) (NH₄)₂Cr₂O₇

Answer 1

Answer:

A red solid is insoluble in water. However it becomes soluble

if some KI is added to water. Heating the red solid in a test

tube results in liberation of some violet coloured fumes and

droplets of a metal appear on the cooler parts of the test

tube. The red solid is

(a) HgI₂

(b) HgO

(c) Pb₃O₄

(d) (NH₄)₂Cr₂O₇

Answer 2

HgI₂ murcuric iodide is the correct option.

Explanation:

• Mercuric iodide is an ionic compound between mercury and iodine.

• It is scarlet red in colour due to the unpaired electron of mercury which leads to the colour of the compound.

• As mercuric iodide is reacted with potassium iodide, it forms a solution which was insoluble in water.

• This is because in potassium iodide, the mercuric iodide forms potassium mercurate which is soluble.

• 2KI +HgI2 = K2(HgI4)

• As mercuric iodide is heated in a test tube, the thermal decomposition of the compound occurs.

• This leads to vaporization of iodine which looks purple in colour.

• The mercury rather than vaporising, condenses in the cooler parts of test tube forming shiny granules.

For more information about mercuric iodide,

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Chemical formula of mercuric iodide cri cros method - Brainly.in

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When mercuric iodide is added to an aqueous solution of KI , then