Embibe Experts Solutions for Chapter: Qualitative Analysis, Exercise 1: Level 1

The solution of a salt in dilute ${\mathrm{H}}_2{\mathrm{SO}}_4$ or acetic acid produces a deep blue colour with the starch iodide solution. The salt contains:

A test tube containing a nitrate, and another containing a bromide and ${\mathrm{MnO}}_2$, are treated with concentrated ${\mathrm{H}}_2{\mathrm{SO}}_4$. The reddish brown fumes evolved are passed through water. The water will be coloured by:

Identify the compound which turns black with ammonia solution.

A mixture of two colourless substances was dissolved in water. When gaseous ${\mathrm{Cl}}_2$ was passed through the solution, containing small quantity of ${\mathrm{CCl}}_4$ a violet colour developed in organic layer. Addition of ${\mathrm{BaCl}}_2$ to the original solution give a white precipitate. The mixture contains:

To avoid the precipitation of hydroxides of ${\mathrm{Ni}}^{2+},{\mathrm{Co}}^{2+},{\mathrm{Mn}}^{2+}$ along with those of the third group cations, the solutions should be:

Nitrite $\left({\mathrm{NO}}_2^{-}\right)$ interferes in the ring-test of nitrate $\left({\mathrm{NO}}_3^{-}\right)$. Some following reagents can be used for the removal of nitrite:

I : Potassium dichromate (s)
II : $\mathrm{CO}{\left({\mathrm{NH}}_2\right)}_2$ (urea)
III : ${\mathrm{NH}}_2{\mathrm{SO}}_3\mathrm{H}$ (sulphamic acid)

IV: Zinc/sodium hydroxide

When ${\mathrm{H}}_2\mathrm{S}$ gas is passed through a hot acidic aqueous solution containing ${\mathrm{Al}}^{3+}, {\mathrm{Cu}}^{2+}, {\mathrm{Pb}}^{2+}$ and ${\mathrm{Ni}}^{2+}$, a precipitate is formed which consists of:

Which of the following is not precipitated as a sulphide by passing ${\mathrm{H}}_2\mathrm{S}$ in the presence of concentrated $\mathrm{HCl}?$