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$32\text{ g mol}^{-1}$). Molar mass of barium sulphate is 233 g mol⁻¹$233\text{ g mol}^{-1}$.

Core Logic

In structure 3, there are positive formal charges on two adjacent atoms (Oxygen and the Carbon adjacent to it). Like charges on adjacent atoms cause extreme electrostatic repulsion, making the structure highly unstable.

Pattern Recognition

Rules of resonance stability:

• Complete octets are more stable.
• More covalent bonds = more stable.
• Least charge separation is more stable.
• Like charges on adjacent atoms create massive destabilization (Least stable scenario).

Chapter Mix

Class 11 Chemistry: Organic Chemistry - Some Basic Principles and Techniques

Core Logic

A. Propanal (CH₃CH₂CHO$CH_3CH_2CHO$) and propanone (CH₃COCH₃$CH_3COCH_3$) have different functional groups (aldehyde vs ketone) but the same molecular formula. They are functional isomers. (Correct)

B. Ethoxyethane (C₂H₅-O-C₂H₅$C_2H_5-O-C_2H_5$) and methoxypropane (CH₃-O-C₃H₇$CH_3-O-C_3H_7$) differ in the alkyl chains attached to the polyvalent oxygen atom. They are metamers. (Correct)

C. But-2-ene shows geometrical isomerism (cis-trans), but no optical isomerism as it lacks a chiral center. (Incorrect)

D. But-1-ene and but-2-ene differ in the position of the double bond. They are position isomers, not functional isomers. (Incorrect)

E. Pentane (straight chain) and 2,2-dimethyl propane (branched chain) have the same formula C₅H₁₂$C_5H_{12}$ but different carbon skeletons. They are chain isomers. (Correct)

Correct statements: A, B, and E.

Pattern Recognition

Metamerism arises when there is a difference in the alkyl groups attached to a polyvalent functional group (e.g., -O-, -S-, -NH-, -CO-).

Chapter Mix

Class 11 Chemistry: Organic Chemistry - Some Basic Principles and Techniques

Core Logic

• A. 2-Methylpropene and but-1-ene differ in carbon chain structure arrow$\rightarrow$ III. Chain isomers
• B. Cis-but-2-ene and trans-but-2-ene differ in spatial arrangement arrow$\rightarrow$ I. Stereoisomers
• C. 2-Butanol (alcohol) and diethyl ether (ether) have different functional groups arrow$\rightarrow$ II. Functional isomers (Note: matches with II/IV based on pairing context in solution)
• D. But-1-ene and but-2-ene differ in position of double bond arrow$\rightarrow$ IV. Position isomers

Step 1: Final Conclusion

Matching respective pairs correctly yields option (2): A-III, B-I, C-II, D-IV.

Pattern Recognition

Sees: Match list of isomerism pairs. Trap: Mixing up position and chain isomers for alkenes.

Chapter Mix

Class 11 Chemistry: Organic Chemistry - Some Basic Principles and Techniques

Core Logic

Nucleophilicity generally parallels basicity among related species (when comparing oxygen-centered nucleophiles in similar environments). Stability order of corresponding conjugate acids/anions is reverse of nucleophilicity or basicity strength. Basicity/Nucleophilicity order: ^-OH > PhO^- > CH₃COO^- > ClO₄^-$^-\text{OH} > \text{PhO}^- > \text{CH}_3\text{COO}^- > \text{ClO}_4^-$.

Step 1: Final Conclusion

Thus, option (4) represents the correct nucleophilicity order.

Pattern Recognition

Sees: Nucleophilic substitution rate and nucleophilicity order. Trap: Confusing leaving group ability with nucleophile strength.

Chapter Mix

Class 11 Chemistry: Organic Chemistry - Some Basic Principles and Techniques