The number of white coloured salts among the following is .... (a) SrSO4 (b) Mg(NH4)PO4 (c) BaCrO4 (d) Mn(OH)2 (e)…

Solution & Explanation

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

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Q jee_main_2024_29_january_evening Chromatographic Separations

Chromatographic technique/s based on the principle of differential adsorption is/are A. Column chromatography B. Thin layer chromatography C. Paper chromatography Choose the most appropriate answer from the options given below:

A. B only
B. A only
C. A & B only
D. C only

Solution

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

Q87 jee_main_2024_29_jan_morning Organic Functional Groups

Number of compounds among the following which contain sulphur as heteroatom is Furan, Thiophene, Pyridine, Pyrrole, Cysteine, Tyrosine

Numerical Answer. Answer: 2 to 2

Solution

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

Organic Functional Groups diagram for Q87 - JEE Main 2024 Morning

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

Chapter Mix

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Solution & Explanation

Core Logic

Step 1: Count White Salts

Pattern Recognition

Chapter Mix

Reference Study Guides

More Principles Related to Practical Chemistry Previous-Year Questions — Page 2

Solution

Related Formula

Core Logic

Step 1: Final Selection

Pattern Recognition

Chapter Mix

Solution

Core Logic

Step 1: Final Count

Chapter Mix

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Solution & Explanation

Core Logic

Step 1: Count White Salts

Pattern Recognition

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Reference Study Guides

More Principles Related to Practical Chemistry Previous-Year Questions — Page 2

Solution

Related Formula

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Step 1: Final Selection

Pattern Recognition

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Solution

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Step 1: Final Count

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