Test: JEE Main 35 Year PYQs- Organic Chemistry Some Basic Principles & Technique - JEE MCQ

Statement -1 is false beca use aryl halides do not undergo nucleophilic substitution under ordinary conditions. This is due to resonance, because of which the carbon–chlorine bond acquires partial double bond character, hence it becomes shorter and stronger and thus cannot be replaced by nucleophiles.

its in termediate carbocation is more stable than the one in benzene.

Statement-1 is correct. Statement-2 is incorrect because compound can be chiral even in the absence of chiral atoms.

–CH₃ group has + I effect , as number of –CH₃ group increases, the inductive effect increases.
Therefore the correct order is

CH₃– CH₂– < (CH₃)₂CH– < (CH₃)₃C –

Sterioisomerism involve those isomers which contain same ligands in their co-ordination spheres but differ in the arrangement of these ligands in space. Stereoisomerism is of two type geomerical isomerism and optical isomerism. In geomerical isomerism ligands occupy different positions around the central metal atom or ion.

NOTE : In optical isomerism isomers have same formula but differ in their ability to rotate directions of the plane of polarised light.

 does not show geometrical isomerism due to presence of two similar Cl atoms on the same C-atom. Geometrical isomerism is shown by compounds in which the groups/atoms attached to C = C are different.

Amino acids contain – NH₂ and – COOH groups e.g

The correct name is 3 - methylbut - 2 - ol

In molecules (a), (c) and (d), the carbon atom has a multiple bond, only (b) has sp³ hybridization.

A mixture of equal amount of two enantiomers is called a racemic mixture. A racemic mixture does not rotate plane– polarized light. They are optically inactive because for every molecule in a racemic mixture that rotate plane of polarized light in one direction, there is a mirror image molecule that rotates the plane in oppsite direction.

TIPS/Formulae : Stereoisomerism is of two types i.e., geometrical isomerism and optical isomerism
Both the structures shows sterioisomerism. Structure I shows geometrical isomerism as it contains two different atoms(H) and groups (CH₃) attached to each carbon containing double bond.

Structure II shows optical isomerism as it contains a chiral carbon (attached to four different group) atom.

The hydrolysis of t-butyl bromide is an example of S_N1 reaction. The reaction consists of two steps.

The anion HCOO⁻ has two resonating structures in which double bond occurs on both xygen atoms. So, the bond length of both the CO bonds is equal.

C_nH_2nO₂ is general formula for carboxylic acid

NOTE : Among isomeric alkanes, the straight ch ain isomer has higher boiling point than the branched chain isomer. The greater the branching of the chain, the lower is the boiling point. Further due to the presence of π electrons, these moleculs are slightly polar and hence have higher boiling points than the corrosponding alkanes.
Thus B.pt. follows the order alkynes > alkene > alkanes (straight chain) > branched chain alkanes.

IUPAC name –  3, 3-Dimethyl -1 cyclohexanol

NOTE : The compounds containing two similar assymmetric C-atoms have plane of symmetry and exist in Meso form.

Cl^– is the best leaving group among the given option.

Only 2- cylcopropyl butane has a chiral centre.

In aroma tic acids presence of electron withdrawing substituent e.g. –NO₂ disperses the negative charge of the anion and stablises it and hence increases the acidity of the parent benzoic acid.
Further o-isomer will have higher acidity than corresponding m and p isomers. Since nitro group at p-position have more pronounced electron withdrawing than –NO₂ group at m-position hence the correct order is the one given above.

Lone pair of electrons present on the  nitrogen of  benzyl amine is not involved  in resonance

1-chloropentane is not chiral while others are chiral in nature

Free radicals are electrically neutral, unstable and very reactive on account of the presence of odd electrons.

In moving down a group, the basicity and nucleophilicity are inversely related, i.e. nucleophilicity increases while basicity decreases. In going from left to right across a period, the basicity and nucleophilicity are directly related. Both of the characteristics decrease as the electronegativity of the atom bearing lone pair of electrons increases. If the nucleophilic centre of two or more species is same, nucleophilicity parallels basicity, i.e. more basic the species, stronger is its nucleophilicity.
Hence based on the above facts, the correct order of nucleophilicity will be

when X is Cl the C–X bond is more polar and  ionic which leaves the compound more reactive for nucleophilic substitution reaction.

The order of stability of free radicals

The stabilisation of first two is due to resonance and last two is due to inductive effect.