D-And F-Block Elements Ques 482
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
Options:
A) $ HgI_2 $
B) $ HgO $
C) $ Pb_3O_4 $
D) $ {{(NH_4)}_2}Cr_2O_7 $
Show Answer
Answer:
Correct Answer: A
Solution:
When KI is added to mercuric iodide it disssolve in it and form complex. $ \underset{\begin{smallmatrix} red,,solid \\ (insoluble) \end{smallmatrix}}{\mathop{HgI_2}},+KI\to \underset{(soluble)}{\mathop{K_2[HgI_4]}}, $ On heating $ HgI_2 $ decomposes as $ HgI_2\rightarrow Hg+\underset{( violetvapours )}{\mathop{I_2}}, $
