When a salt is treated with sodium hydroxide solution it gives gas X. On passing gas X through reagent Y a brown coloured precipitate is formed. X and Y respectively, are:

### Related Formula mathrmNi^2+ + 2mathrmdmg^- rightarrow [mathrmNi(mathrmdmg)_2] downarrow quad text(Rosy Red Complex)$$\mathrm{Ni}^{2+} + 2\mathrm{dmg}^- \rightarrow [\mathrm{Ni}(\mathrm{dmg})_2] \downarrow \quad \text{(Rosy Red Complex)}$$ ### Core Logic In basic medium (typically using ammonium hydroxide), nickel(II$II$) ions react cleanly with dimethylglyoxime (textdmgH$\text{dmgH}$) to generate a stable, neutral coordination complex containing structural hydrogen bonding. This complex isolates out of solution as a highly signature brilliant rosy red precipitate. ### Step 1: Finalization Therefore, dimethyl glyoxime is universally utilized for the quantitative and qualitative determination of textNi^2+$\text{Ni}^{2+}$ ions. ### Pattern Recognition Nickel plus dmg in alkaline solution yields a signature rosy red chelate stabilized via symmetrical internal hydrogen bonds. ### Evaluation Rubric / Model Answer null ### Chapter Mix Class 12 Chemistry: Principles of Qualitative Analysis

### Related Formula 2mathrmK_2[mathrmHgI_4] + mathrmNH_3 + 3mathrmKOH rightarrow mathrmHgOcdotmathrmHg(mathrmNH_2)mathrmI downarrow + 7mathrmKI + 2mathrmH_2mathrmO$$2mathrm{K}_2[mathrm{HgI}_4] + mathrm{NH}_3 + 3mathrm{KOH} \rightarrow mathrm{HgO}\cdot\mathrm{Hg}(mathrm{NH}_2)mathrm{I} \downarrow + 7mathrm{KI} + 2mathrm{H}_2mathrm{O}$$ ### Core Logic Nessler's reagent (K_2[HgI_4]$K_2[HgI_4]$ in alkaline solution) reacts explicitly with ammonia gas (NH_3$NH_3$) or ammonium ions to create an insoluble iodide of Millon's base (textHgOcdottextHg(textNH_2)textI$\text{HgO}\cdot\text{Hg}(\text{NH}_2)\text{I}$). This characteristic complex showcases a signature brown structural coloration. ### Step 1: Finalization Thus, the unknown tracking gas 'X' is uniquely identified as ammonia (NH_3$NH_3$). ### Pattern Recognition Ammonia detection relies directly upon alkaline potassium tetraiodomercurate(II) resulting in brown Millon's base precipitations. ### Evaluation Rubric / Model Answer null ### Chapter Mix Class 12 Chemistry: Principles of Qualitative Analysis

### Related Formula Na_2S + H_2SO_4 rightarrow Na_2SO_4 + H_2S$$Na_2S + H_2SO_4 \rightarrow Na_2SO_4 + H_2S$$ (CH_3COO)_2Pb + H_2S rightarrow PbS + 2CH_3COOH$$(CH_3COO)_2Pb + H_2S \rightarrow PbS + 2CH_3COOH$$ ### Core Logic When a salt containing sulphide is warmed with dilute H_2SO_4$H_2SO_4$, H_2S$H_2S$ gas is evolved. H_2S$H_2S$ gas turns lead acetate paper black due to the formation of lead sulphide (PbS$PbS$), not lead sulphite. Thus, Statement I is correct, but Statement II is incorrect. ### Pattern Recognition Lead acetate paper test is standard for H_2S$H_2S$ gas, forming black PbS$PbS$. Always watch out for the trap suffix: sulphite (SO_3^2-$SO_3^{2-}$) vs sulphide (S^2-$S^{2-}$). ### Evaluation Rubric / Model Answer null ### Chapter Mix Class 11 Chemistry: Qualitative Analysis Class 11 Chemistry: p-Block Elements

### Core Logic Analyzing the colors of the given salts: Lead sulphate (PbSO_4$PbSO_4$) is white. Ammonium sulphide ((NH_4)_2S$(NH_4)_2S$) is soluble/colorless in solution. Lead iodide (PbI_2$PbI_2$) is bright yellow. Ammonium arsinomolybdate is yellow. ### Evaluation Rubric / Model Answer null ### Chapter Mix Class 12 Chemistry: Salt Analysis