Test: MCQs (One or More Correct Option): Organic Chemistry - Some Basic Principles & Technique | JEE Advanced - JEE MCQ

Resonating structures differ in bonding pattern.

Higher the stability of the corresponding anion, more will be the acidic character of the parent compound.

Higher stability of acetate ions than phenoxide ion is due to equivalent resonating structures in the former

1, 4-Dichlorobenzene (p-dichlorobenzene) and trans1, 2-dichloroethene have zero dipole moment because of their symmetrical structures.

In n-butane, Cl can add at either the first or second carbon giving two isomers.

 will give three isomers with Cl group at either of the CH₃ groups, second C-atom and 3rd C-atom.
Benzene forms only one single derivative.

Option (d) :  will again give two isomers with Cl at either one of the CH₃ groups or on the central C-atom

An asymmetric carbon atom is one which is attached with 4 different groups. Hence (c) & (d) are correct.

TIPS/Formulae : Conjugate base of strong acid is weak while conjugate base of a weak acid is stronger.
Acidic strength of acids, HOH > CH ≡ CH > NH₃ > CH₃.CH₃ Hence the order of strength of bases,

Only 2-butene and 1-phenylpropene can show geometrical isomerism (cis-and trans-isomers).

Order of acidic strength CH₃OH > CH ≡ CH > C₆H₆ > C₂H₆ ; CH₃OH is most acidic because O is more electronegative than C and capable of accommodating negative charge in CH₃O– Although alcohols are neutral towards the litmus paper.

TIPS/Formulae :

For a carbonyl compound to show tautomerism, it must have at least one H at the α – carbon atom. (a), (c) and (d) show tautomerism.

 Tautomerism is not possible

NOTE : An aromatic species will have :
(4n + 2) p electrons     (by Huckel’s Rule)
planar structure           (due to resonance)
cyclic structure             (due to presence of sp² - hybrid carbon atoms).

E and F ; and also E and G differ in position of atom (H), so these are tautomers (not resonating structures.
Geometrical isomers are also diastereomers).

The given molecule although posseses neither centre of symmetry nor a plane of symmetry (hence optically active) but it has an axis of symmetry (C_n).
NOTE : A C_n axis of symmetry is an axis about which the molecule can be rotated by 360°/n to produce a molecule indistinguishable from the original molecule.

Structural formula of 2, 2-dimethylbutane is

(I) Newman projection using C₁–C₂ bond

(II) Newman projection using C₃–C₂ bond

b and c, being antiaromatic, are unstable at room temperature.

Converting all the structures in the Fischer projection

M and N are diastereoisomers M and O are identical M and P are enantiomers M and Q are diastereoisomers Hence, the correct options are a, b, c.

In tert butyl cation, carbon bearing positive charge has one vacant p-orbital hence it is σ–p (empty) conjugation or hyperconjugation.

In 2-butene, hyperconjugation is between σ→π* bond.