Among the following cations, the number of cations which will give characteristic precipitate in their identification tests with K₄[Fe(CN)₆]$\mathrm{K}_4[\mathrm{Fe}(\mathrm{CN})_6]$ is: Cu²⁺$\mathrm{Cu}^{2+}$ , Fe³⁺$\mathrm{Fe}^{3+}$ , Ba²⁺$\mathrm{Ba}^{2+}$ , Ca²⁺$\mathrm{Ca}^{2+}$ , NH₄^+$\mathrm{NH}_4^+$ , Mg²⁺$\mathrm{Mg}^{2+}$ , Zn²⁺$\mathrm{Zn}^{2+}$

Core Logic

Analyzing the colors of the given precipitates/salts from qualitative analysis: (a) SrSO₄$SrSO_4$ - White precipitate (Group V/Sulfates) (b) Mg(NH₄)PO₄$Mg(NH_4)PO_4$ - White crystalline precipitate (Group VI test for Mg) (c) BaCrO₄$BaCrO_4$ - Yellow precipitate (Test for Barium) (d) Mn(OH)₂$Mn(OH)_2$ - White precipitate (turns brown on standing due to oxidation to MnO₂$MnO_2$) (e) PbSO₄$PbSO_4$ - White precipitate (Group I / Sulfates) (f) PbCrO₄$PbCrO_4$ - Yellow precipitate (Chrome yellow) (g) AgBr$AgBr$ - Pale yellow precipitate (h) PbI₂$PbI_2$ - Yellow precipitate (Golden spangles) (i) CaC₂O₄$CaC_2O_4$ - White precipitate (Calcium oxalate) (j) [Fe(OH)₂(CH₃COO)]$[Fe(OH)_2(CH_3COO)]$ - Blood red / Brown red coloration (Basic iron acetate, acetate radical test)

Step 1: Count White Salts

The salts that are white are:

• SrSO₄$SrSO_4$
• Mg(NH₄)PO₄$Mg(NH_4)PO_4$
• Mn(OH)₂$Mn(OH)_2$
• PbSO₄$PbSO_4$
• CaC₂O₄$CaC_2O_4$

Total count = 5.

Pattern Recognition

Most alkali/alkaline-earth metal salts (sulfates, oxalates, phosphates) and lead(II) sulfate/chloride are white. Chromates (BaCrO₄$BaCrO_4$, PbCrO₄$PbCrO_4$) are distinctly yellow. Silver halides range from white (AgCl$AgCl$) to pale yellow (AgBr$AgBr$) to yellow (AgI$AgI$).

Chapter Mix

Class 11 Chemistry: Principles Related to Practical Chemistry Class 12 Chemistry: The d-and f-Block Elements

Related Formula

Classification of chromatography based on adsorption vs partition parameters.

Core Logic

Chromatography techniques are broadly divided into two main categories based on their operating principles:

• Adsorption Chromatography: Relies on the differential adsorption of components on the surface of a stationary phase. Both Column Chromatography and Thin Layer Chromatography (TLC) operate on this principle.
• Partition Chromatography: Relies on continuous differential partitioning of components between stationary and mobile liquid phases. Paper Chromatography is a prime example of this category.

Step 1: Final Selection

Thus, statements A and B are correct, matching choice (3).

Pattern Recognition

Remember: Column and Thin Layer chromatography are adsorption-based, while paper chromatography relies on partition mechanisms.

Chapter Mix

Class 11 Chemistry: Principles of Practical Chemistry

Core Logic

Let us check the chemical structure of each compound given in the list to determine if it contains a Sulphur (S) atom.

• Furan: A 5-membered heterocyclic aromatic ring containing Oxygen (C₄H₄O$C_4H_4O$). No Sulphur.
• Thiophene: A 5-membered heterocyclic aromatic ring containing Sulphur (C₄H₄S$C_4H_4S$). Contains Sulphur.
• Pyridine: A 6-membered heterocyclic aromatic ring containing Nitrogen (C₅H₅N$C_5H_5N$). No Sulphur.
• Pyrrole: A 5-membered heterocyclic aromatic ring containing Nitrogen (C₄H₄NH$C_4H_4NH$). No Sulphur.
• Cysteine: A naturally occurring α$\alpha$-amino acid with a thiol side chain (-CH₂-SH$-CH_2-SH$). Contains Sulphur.
• Tyrosine: An α$\alpha$-amino acid with a phenol side chain. No Sulphur.

Step 1: Final Count

Only Thiophene and Cysteine contain a sulphur heteroatom. Total number = 2.

Chapter Mix

Class 11 Chemistry: Organic Chemistry Some Basic Principles and Techniques Class 12 Chemistry: Biomolecules