Question 1

The following carbocation is stabilized by the interaction of the empty p orbital with

Accepted Answer

The given carbocation has a positively charged carbon atom that is sp^2 hybridized, possessing an empty unhybridized p-orbital. This empty p-orbital is stabilized by hyperconjugation, where the filled C-H bonding orbitals of the adjacent methyl group overlap with the empty p-orbital to donate electron density. Additionally, it is stabilized by resonance, where the filled bonding orbitals of the adjacent benzene ring overlap with the empty p-orbital to delocalize electrons. Thus, the stabilizatio

Question 2

The pair of molecules that are metamers among the following is :

Accepted Answer

Metamerism is a type of structural isomerism where isomers have the same molecular formula but differ in the nature of the alkyl groups attached to the same polyvalent functional group (such as - O -, - S -, - NH -, - CO -). In option (1), CH _3 CH _2 CH _2 OH and CH _3- CH(OH) - CH _3 are position isomers because the position of the - OH group differs. In option (2), CH _3 CH _2 CH _2 CH _2 CH _3 and ( CH _3)_2 CHCH _2 CH _3 are chain isomers because the carbon skeleton differs. In option (3),

Question 3

During Lassaigne's test, the elements present in an organic compound are converted from :

Accepted Answer

In Lassaigne's test, an organic compound is fused with sodium metal. The elements present in the organic compound, such as nitrogen, sulphur, and halogens, are initially present in covalent form. During the fusion process, these elements react with sodium to form ionic sodium salts. For example, nitrogen and carbon form sodium cyanide ( NaCN ), sulphur forms sodium sulphide ( Na _2 S ), and halogens form sodium halides ( NaX ). Therefore, the elements are converted from covalent form to ionic fo

Question 4

The correct IUPAC name of the following compound is :

Accepted Answer

1. Identify the longest continuous carbon chain: The longest chain in the given structure contains 7 carbon atoms. Therefore, the parent alkane is heptane. 2. Identify the substituents: There is an ethyl group ( -CH _2 CH _3) and a methyl group ( -CH _3) attached to the main chain. 3. Number the carbon chain: - Numbering from left to right gives the substituents at positions 3 (ethyl) and 5 (methyl). - Numbering from right to left gives the substituents at positions 3 (methyl) and 5 (ethyl). 4.

Question 5

Arrange the following compounds in the increasing order of polarity A. CH_3CH_2OCH_2CH_3 B. CH_3CH_2OH C. CH_3COCH_3 D. CH_3COOH Choose the correct answer from the options given below.

Accepted Answer

The polarity of organic compounds depends on the presence of polar bonds and their ability to form hydrogen bonds. Diethyl ether (A) has C-O bonds but lacks hydrogen bonding capabilities, making it the least polar among the given compounds. Acetone (C) contains a highly polar C=O double bond, making it more polar than ethers, but it cannot act as a hydrogen bond donor. Ethanol (B) contains an -OH group, which allows it to form strong intermolecular hydrogen bonds, making it more polar than keton

Question 6

Which one of the following compounds can exist as cis-trans isomers?

Accepted Answer

For GI in alkene, each terminal individually must have different atoms/groups attached to it. For GI in cyclo-alkane, at least two sp ^3 C of ring individually must have different atoms/groups attached to it.

Question 7

Which one of the following reactions does NOT belong to "Lassaigne's test" ?

Accepted Answer

2 CuO + C [ ] 2 Cu + CO _2 "Lassaigne's test" is used to detect Nitrogen, Halogen, Sulphur, Phosphorus. 4^ th option is detection of carbon, it is not "Lassaigne's test".

Question 8

Among the given compound I-III, the correct order of bond dissociation energy of C - H bond marked with * is :-

Accepted Answer

Bond dissociation energy 1 Stability of free radical formed after C-H bond fission homolytically Stability order III > I > II Bond dissociation energy order II I III.

Question 9

Match List-I with List-II array |l|l|l|l| & List-I (Mixture) & & List-II (Method of Separation) \ A. & CHCl _3+ C _6 H _5 NH _2 & I. & Distillation under reduced pressure \ B. & Crude oil in petrole

Accepted Answer

Correct Match array |l|l|l|l| CHCl _3+ C _6 H _5 NH _2 & & Simple distillation \ Crude oil in petroleum industry & & Fractional distillation (III) \ Glycerol from & & Distillation under spent-lye reduced pressure (I) \ Aniline-water & & Steam distillation (II) \ array

Question 10

The correct IUPAC name of the compound

Accepted Answer

4-ethyl-1-fluoro-2-nitrobenzene

Question 11

On complete combustion, 0.3 g of an organic compound gave 0.2 g of CO _2 and 0.1 g of H _2 O . The percentage composition of carbon and hydrogen in the compound, respectively is:

Accepted Answer

Percentage of carbon = 12 m _2 100 44 m m = mass of organic compound =0.3 ~g m _2= mass of carbon dioxilde =0.2 ~g \% C= 12 0.2 100 44 0.3 =18.18 \% Percentage of hydrogen = 2 m _1 100 18 m m _1= mass of water =0.1 ~g \% H = 2 0.1 100 18 0.3 =3.70 \%

Question 12

Methyl group attached to a positively charged carbon atom stabilizes the carbocation due to

Accepted Answer

Methyl group attached to a positively charged carbon atom stabilizes the carbocation due to hyperconjugation and +I effect.

Question 13

On heating, some solid substances change from solid to vapour state without passing through liquid state. The technique used for the purification of such solid substances based on the above principle

Accepted Answer

(1) Sublimation : It is the purification technique based on principle that on heating, some solid substances change from solid to vapour state without passing through liquid state. (2) Distillation : It is used to separate volatile liquids from non-volatile impurities and the liquids having sufficient difference in their boiling point. (3) Chromatography : It is based on separation by using stationary and mobile phase. (4) Crystallization : It is based on difference in the solubilities of the co

Question 14

Given below are two statements: Statement I : The boiling point of three isomeric pentanes follows the order n-pentane isopentane neopentane Statement II : When branching increases, the molecule attai

Accepted Answer

Both statement I and statement II are correct. array r Boiling point of n -pentane =309 ~K \ isopentane =301 ~K \ neopentane =282.5 array As branching increases molecules attain the shape of a sphere results in smaller area of contact thus weak intermolecular forces between spherical molecules, which are overcome at relatively lower temperature. Leading to decrease in boiling point.

Question 15

The most stable carbocation among the following is :

Accepted Answer

The stability of carbocation can be described by the hyperconjugation. Greater the extent of hyperconjugation, more is the stability of carbocation. Stability order of carbocations =(3) (1) (4) (2)

Question 16

A compound with a molecular formula of C _6 H _ 14 has two tertiary carbons. Its IUPAC name is :

Accepted Answer

Answer option index: 1

Question 17

A steam volatile organic compound which is immiscible with water has a boiling point of 250^ C . During steam distillation, a mixture of this organic compound and water will boil :

Accepted Answer

If one of the substances in the mixture is water and the other, a water insoluble substance, then the mixture will boil close to but below, 373 ~K (100^ C ).

General Organic Chemistry — Previous Year Questions & Solutions