JEE Main · 2023 · 30 Jan 2023 · Shift 2 · Practical and Analytical Chemistry

Formulae for Nessler's reagent is:

(A) $KHg_{2} I_{2}$
(B) $KHgI_{3}$
(C) $K_{2} HgI_{4}$ ✓ Correct
(D) $HgI_{2}$

Answer: (C)

Solution

Nessler's reagent is prepared by dissolving mercury(II) iodide in an excess of potassium iodide and then making the solution alkaline. The mercury is taken up as the tetraiodo complex, four iodide ions gathered about one mercury and balanced by two potassium ions. The reagent, used to detect ammonia, therefore has the formula

K_{2} HgI_{4}

JEE Main · 2023 · 30 Jan 2023 · Shift 2 · Single correct option

Practise more: all JEE Main PYQs on Practical and Analytical Chemistry →

More JEE Main questions on Practical and Analytical Chemistry

Consider the following reactions.
$PbCl_{2} + K_{2} CrO_{4} \to A + 2 KCl$ (Hot solution)
$A + NaOH ⇌ B + Na_{2} CrO_{4}$ …
JEE Main 2026View solution →
In Carius method, 0.75 g of an organic compound gave 1.2 g of barium sulphate, find percentage of sulphur (molar mass $32 g mol^{- 1}$ ). Molar mass of barium sulphate is $233 g mol^{- 1}$ .
JEE Main 2026View solution →
Sodium fusion extract of an organic compound (Y) with $CHCl_{3}$ and chlorine water gives violet color to the $CHCl_{3}$ layer. 0.15 g of $(Y)$ gave 0.12 g of the silver halide precipitate in Carius method. Percentage of halogen in the compound …
JEE Main 2026View solution →
When 1 g of compound ( X ) is subjected to Kjeldahl's method for estimation of nitrogen, 15 $mL, 1 M H_{2} SO_{4}$ was neutralized by ammonia evolved. The percentage of nitrogen in compound $(X)$ is :
JEE Main 2026View solution →
Identify the correct statements:
A. Hydrated salts can be used as primary standard.
B. Primary standard should not undergo any reaction with air.
C. Reactions of primary standard with another substance should be instantaneous and stoichiometric.
D. Primary standard should not be …
JEE Main 2026View solution →
Match List-I with List-II.

List-I: Functional group (detection)
(A) Unsaturation (Baeyer's test)
(B) Alcoholic group (Ceric ammonium nitrate test)
(C) Aldehyde group (Tollen's reagent)
(D) Phenolic group ( $FeCl X_{3}$ test)

List-II: Change observed during detection
(I) Red co …
JEE Main 2026View solution →