Organic Chemistry - Some Basic Principles and Techniques Previous Year Questions — JEE Main Chemistry
101 past-year Organic Chemistry - Some Basic Principles and Techniques questions from JEE Main (Chemistry) — page 16.
Q66 (2024)
A species having carbon with sextet of electrons and can act as electrophile is called
- $\text{carbon free radical}$
- $\text{carbanion}$
- $\text{carbocation}$
- $\text{pentavalent carbon}$
### Core Logic
{{SOL_IMG1}}
A carbocation has three bonds and an empty p-orbital, yielding a sextet (6) of electrons in its valence shell. Due to its electron deficiency, it acts as a strong electrophile.
### Evaluation Rubric / Model Answer
null
### Chapter Mix
Class 11 Chemistry: Organic Chemistry - Some Basic Principles and Techniques
Q72 (2024)
'Adsorption' principle is used for which of the following purification method?
- $\text{Extraction}$
- $\text{Chromatography}$
- $\text{Distillation}$
- $\text{Sublimation}$
### Core Logic
The fundamental principle used in chromatography (such as column chromatography or thin-layer chromatography) is adsorption. Different components of a mixture are adsorbed to different extents on an adsorbent stationary phase.
### Evaluation Rubric / Model Answer
null
### Chapter Mix
Class 11 Chemistry: Organic Chemistry - Some Basic Principles and Techniques
Q75 (2024)
Given below are two statements:
Statement I: IUPAC name of $HO-CH_2-(CH_2)_3-CH_2-COCH_3$ is 7-hydroxyheptan-2-one.
Statement II: 2-oxoheptan-7-ol is the correct IUPAC name for above compound.
In the light of the above statements. choose the most appropriate answer from the options given below:
- $\text{Statement I is correct but Statement II is incorrect.}$
- $\text{Both Statement I and Statement II are incorrect.}$
- $\text{Both Statement I and Statement II are correct.}$
- $\text{Statement I is incorrect but Statement II is correct.}$
### Core Logic
Structure: $HO-C^7H_2-C^6H_2-C^5H_2-C^4H_2-C^3H_2-C^2(=O)-C^1H_3$
Principal functional group rule: Ketone ($>C=O$) has higher priority over alcohol ($-OH$). Therefore, numbering starts from the right side to give the ketone the lowest possible locant (2).
The carbon chain has 7 carbons, making it heptane.
The $-OH$ group acts as a substituent named 'hydroxy' at position 7.
Correct IUPAC name: 7-hydroxyheptan-2-one.
Thus, Statement I is correct and Statement II is incorrect.
### Evaluation Rubric / Model Answer
null
### Chapter Mix
Class 11 Chemistry: General Organic Chemistry
Q80 (2024)
Match List I with List II
<div style="overflow-x: auto; margin: 1rem 0;"><table style="width: 100%; border-collapse: collapse; text-align: left; font-size: 14px;"><thead><tr><th style="border: 1px solid #888; padding: 8px;">LIST-I (Technique)</th><th style="border: 1px solid #888; padding: 8px;">LIST-II (Application)</th></tr></thead><tbody><tr><td style="border: 1px solid #888; padding: 8px;">A. Distillation</td><td style="border: 1px solid #888; padding: 8px;">I. Separation of glycerol from spent-lye</td></tr><tr><td style="border: 1px solid #888; padding: 8px;">B. Fractional distillation</td><td style="border: 1px solid #888; padding: 8px;">II. Aniline - Water mixture</td></tr><tr><td style="border: 1px solid #888; padding: 8px;">C. Steam distillation</td><td style="border: 1px solid #888; padding: 8px;">III. Separation of crude oil fractions</td></tr><tr><td style="border: 1px solid #888; padding: 8px;">D. Distillation under reduced pressure</td><td style="border: 1px solid #888; padding: 8px;">IV. Chloroform-Aniline</td></tr></tbody></table></div>
Choose the correct answer from the options given below:
- $\text{A-IV, B-I, C-II, D-III}$
- $\text{A-IV, B-III, C-II, D-I}$
- $\text{A-I, B-II, C-IV, D-III}$
- $\text{A-II, B-III, C-I, D-IV}$
### Core Logic
(A) Simple distillation is used to separate a mixture of miscible liquids with a sufficiently large difference in their boiling points, such as chloroform and aniline. (A $\rightarrow$ IV)
(B) Fractional distillation is used to separate crude oil fractions. (B $\rightarrow$ III)
(C) Steam distillation is used to separate steam-volatile substances that are immiscible with water, like an aniline-water mixture. (C $\rightarrow$ II)
(D) Distillation under reduced pressure is used for liquids that decompose at or below their normal boiling points, like separating glycerol from spent lye. (D $\rightarrow$ I)
### Evaluation Rubric / Model Answer
null
### Chapter Mix
Class 11 Chemistry: Organic Chemistry - Some Basic Principles and Techniques
Q58 (2026)
In Carius method, 0.75 g of an organic compound gave 1.2 g of barium sulphate, find percentage of sulphur (molar mass $32\text{ g mol}^{-1}$). Molar mass of barium sulphate is $233\text{ g mol}^{-1}$.
- $4.55\%$
- $10.30\%$
- $21.97\%$
- $16.48\%$
### Related Formula
$$\text{Percentage of Sulphur} = \frac{\text{Mass of } S \text{ in } BaSO_4}{\text{Molar mass of } BaSO_4} \times \frac{\text{Mass of } BaSO_4 \text{ formed}}{\text{Mass of organic compound}} \times 100$$
### Core Logic
Molar mass of $BaSO_4$ = 233 g/mol.
Mass of Sulfur (S) in 1 mole of $BaSO_4$ = 32 g.
Mass of $BaSO_4$ formed = 1.2 g.
Mass of organic compound = 0.75 g.
$$\% \mathrm{S} = \frac{32}{233} \times \frac{1.2}{0.75} \times 100$$
$$\% \mathrm{S} = \frac{32 \times 1.2 \times 100}{233 \times 0.75} = \frac{3840}{174.75} \approx 21.97\%$$
### Evaluation Rubric / Model Answer
null
### Chapter Mix
Class 11 Chemistry: Organic Chemistry - Some Basic Principles and Techniques
