🧪 NEET Practice Test

Organic Chemistry - Chapter 1: Some Basic Principles and Techniques

Time: 135 minutes | Questions: 45 | Maximum Marks: 180

📋 Instructions

📚 Section A: Introduction to Organic Chemistry (Questions 1-8)
Q.1
The molecular formula C6H12O6 represents which characteristic of organic compounds?
Q.2
Which statement about organic compounds is incorrect?
Q.3
The unique ability of carbon to form chains and rings is primarily due to:
Q.4
Hybridization of carbon in CH4, C2H4, and C2H2 respectively is:
Q.5
The bond angles in methane (CH4), ethene (C2H4), and ethyne (C2H2) are respectively:
Q.6
Which compound represents a heterocyclic compound?
Q.7
The classification of organic compounds is primarily based on:
Q.8
Vital force theory was disproved by Wöhler's synthesis of:
🏷️ Section B: IUPAC Nomenclature (Questions 9-16)
Q.9
The IUPAC name of CH3-CH(CH3)-CH2-CH3 is:
Q.10
The IUPAC name of (CH3)3C-CH2-CH3 is:
Q.11
The correct IUPAC name for CH3-CH2-CHBr-CH3 is:
Q.12
The IUPAC name of CH3-CH2-CO-CH3 is:
Q.13
The priority order of functional groups for IUPAC nomenclature is:
Q.14
The IUPAC name of CH3-CH(OH)-CH2-CHO is:
Q.15
In IUPAC nomenclature, the suffix for alkenes is:
Q.16
The IUPAC name of CH3-CH2-CH=CH2 is:
🔄 Section C: Isomerism (Questions 17-25)
Q.17
Compounds having the same molecular formula but different structures are called:
Q.18
Chain isomerism is first exhibited by:
Q.19
The total number of structural isomers possible for C5H12 is:
Q.20
Position isomerism is shown by:
Q.21
Functional isomerism is exhibited by:
Q.22
Metamerism is shown by:
Q.23
CH3-CH2-O-CH2-CH3 and CH3-O-CH2-CH2-CH3 are examples of:
Q.24
Tautomerism is a special case of:
Q.25
The phenomenon where a compound exists as a mixture of two rapidly interconverting isomers is called:
⚗️ Section D: Purification & Separation Techniques (Questions 26-32)
Q.26
Which method is used to separate liquids with different boiling points?
Q.27
Fractional distillation is preferred over simple distillation when:
Q.28
Steam distillation is used for:
Q.29
In column chromatography, the separation is based on:
Q.30
The stationary phase in paper chromatography is:
Q.31
Rf value in thin layer chromatography is defined as:
Q.32
Which is the most polar solvent?
🔍 Section E: Qualitative Analysis - Detection & Tests (Questions 33-40)
Q.33
Lassaigne's test is used to detect:
Q.34
In Lassaigne's test, sodium fusion extract gives a blood red color with FeCl3 due to:
Q.35
Silver nitrate test is used to detect:
Q.36
Fehling's test is positive for:
Q.37
Benedict's test is used to detect:
Q.38
Lucas test is used to distinguish between:
Q.39
Tollens' reagent gives a positive test with:
Q.40
Iodoform test is positive for compounds containing:
📊 Section F: Quantitative Analysis - Estimation (Questions 41-45)
Q.41
In Dumas method for nitrogen estimation, nitrogen is converted to:
Q.42
In Kjeldahl's method, the organic compound is heated with:
Q.43
For estimation of carbon and hydrogen, the organic compound is combusted in the presence of:
Q.44
In Carius method for sulfur estimation, sulfur is converted to:
Q.45
If 0.24 g of an organic compound on combustion gave 0.44 g of CO2 and 0.18 g of H2O, the percentage of carbon in the compound is:
(Atomic masses: C = 12, H = 1, O = 16)

📝 Answer Key & Solutions

Complete answers with explanations for all 45 questions

Q. No. Answer Topic Explanation
1 C Molecular Formula Molecular formula shows exact number of each atom type in one molecule
2 C Organic Properties Not all organic compounds have low melting/boiling points (e.g., glucose)
3 B Carbon Properties Tetravalency allows 4 bonds; catenation allows chain formation
4 A Hybridization CH₄: sp³, C₂H₄: sp², C₂H₂: sp hybridization
5 A Bond Angles sp³: 109.5°, sp²: 120°, sp: 180°
6 C Heterocyclic Pyridine contains nitrogen in ring structure
7 C Classification Both functional groups and carbon skeleton determine classification
8 B History Wöhler synthesized urea (organic) from ammonium cyanate (inorganic)
9 A IUPAC Naming Longest chain: 4 carbons, methyl at position 2
10 A IUPAC Naming 4-carbon chain with two methyls at position 2
11 B IUPAC Naming Bromine at 2nd position in 4-carbon chain
12 D IUPAC Naming Both butanone and 2-butanone are correct IUPAC names
13 A Functional Priority Carboxylic acid has highest priority in IUPAC nomenclature
14 A IUPAC Naming Aldehyde takes priority; OH at position 3 from aldehyde carbon
15 B IUPAC Suffixes Alkenes have -ene suffix
16 C IUPAC Naming But-1-ene: double bond starts at carbon 1
17 B Isomerism Definition of isomers: same molecular formula, different structure
18 C Chain Isomerism C₄H₁₀ has butane and isobutane (first chain isomers)
19 B Structural Isomers C₅H₁₂: n-pentane, isopentane, neopentane (3 isomers)
20 A Position Isomerism OH group at different positions: 1-propanol vs 2-propanol
21 C Functional Isomerism Both alcohol-ether and aldehyde-ketone are functional isomers
22 D Metamerism All compounds with divalent functional groups show metamerism
23 C Metamerism Different alkyl groups on either side of oxygen
24 B Tautomerism Rapid equilibrium between different functional forms
25 B Tautomerism Dynamic equilibrium between tautomeric forms
26 B Separation Distillation separates based on boiling point differences
27 B Distillation Fractional distillation for close boiling points (<25°C)
28 B Steam Distillation For temperature-sensitive, water-immiscible compounds
29 A Chromatography Column chromatography uses differential adsorption
30 D Paper Chromatography Water molecules adsorbed on cellulose fibers
31 B Rf Value Rf = distance moved by compound / distance moved by solvent
32 D Polarity Methanol has highest polarity due to -OH group
33 B Lassaigne's Test Detects nitrogen, sulfur, and halogen elements
34 C Lassaigne's Test Blood red color indicates both N and S present
35 C Silver Nitrate Test AgNO₃ test specifically detects halogens
36 C Fehling's Test Positive only for aliphatic aldehydes, not aromatic
37 A Benedict's Test Detects reducing sugars (free aldehyde/ketone groups)
38 A Lucas Test Distinguishes 1°, 2°, and 3° alcohols by rate of reaction
39 D Tollens' Test Positive for aldehydes and α-hydroxy ketones
40 B Iodoform Test Positive for CH₃CO- or CH₃CH(OH)- groups
41 B Dumas Method Nitrogen converted to N₂ gas and measured
42 B Kjeldahl Method Uses concentrated H₂SO₄ for nitrogen estimation
43 B C,H Estimation Combustion in oxygen converts C to CO₂, H to H₂O
44 D Carius Method Sulfur converted to BaSO₄ precipitate for estimation
45 B Calculation %C = (12×0.44×100)/(44×0.24) = 50%

📐 Important Formulas for Quantitative Analysis

Percentage of Carbon:

%C = (12 × mass of CO2 × 100) / (44 × mass of compound)

Percentage of Hydrogen:

%H = (2 × mass of H2O × 100) / (18 × mass of compound)

Percentage of Nitrogen (Kjeldahl):

%N = (1.4 × Volume of acid × Normality) / Weight of compound

Rf Value:

Rf = Distance traveled by solute / Distance traveled by solvent front

🎯 Scoring Guide

Score Range Questions Correct Performance Level
160-180 40-45 Excellent
120-159 30-39 Good
80-119 20-29 Average
Below 80 Below 20 Needs Improvement

🧪 NEET Organic Chemistry Practice Test - Chapter 1 🧪

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