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Q.
$K_2HgI_4$ is used to lest the following
Rajasthan PMTRajasthan PMT 2007The p-Block Elements
Solution:
Nessler's reagent is $K _{2}\left[ HgI _{4}\right] .$ It is used in identification of $NH _{4}^{+}$in inorganic salt analysis, The compounds having $NH _{4}^{+}$ion give brown ppt. when Nessler's reagent and $KOH$ is added.