Exams › JEE Advanced › Chemistry

Consider the two statements: Statement I: Hyperconjugation is a permanent effect. Statement II: Hyperconjugation in the ethyl cation (CH3-CH2+) involves overlap of a C(sp3)-H (1s) sigma bond with the empty 2p orbital on the adjacent (cationic) carbon. Choose the correct option.

1. Both statement I and statement II are false
2. Statement I is incorrect but statement II is true
3. Statement I is correct but statement II is false
4. Both Statement I and statement II are true.

Correct answer: Both Statement I and statement II are true.

Solution

Hyperconjugation is a permanent electronic effect (like inductive and resonance effects), present even without an attacking reagent, so Statement I is true. In the ethyl cation, the sigma electrons of a C(sp3)-H bond of the methyl group delocalize into the empty 2p orbital of the positively charged carbon - exactly the description in Statement II - so Statement II is true.

Related JEE Advanced Chemistry questions

• The transformation of C2H5CON to C2H5NCO demonstrates a rearrangement involving the migration of an alkyl group to which site?
• The hyperconjugative stabilities of tert-butyl cation and 2-butene, respectively, are due to -
• How many valid pairs (P1, P2) are possible such that 'P1-methylpent-P2-yne' is a correct IUPAC name, where P1 denotes the position of the methyl substituent and P2 denotes the position of the triple bond?
• In the Reimer-Tiemann reaction (phenol + CHCl3 + NaOH, heated), which intermediate is formed on the pathway to salicylaldehyde?
• How many of the following groups show a negative inductive (-I) effect? (a) -Cl (b) -CH3 (c) -O(-) (d) -COO(-) (e) -CMe3 (f) -F (g) -NH2 (h) -OH (i) -NO2 (j) -N=O (k) (+)-NH3
• How many of the following compounds are more acidic than ethanol (CH3-CH2-OH)? (a) CF3-CH2-OH (2,2,2-trifluoroethanol) (b) CH3-CF2-OH (1,1-difluoroethanol) (c) CH3-C(=O)-OH (acetic acid) (d) CH3-CH(OH)-CH3 (propan-2-ol)

⚔️ Practice JEE Advanced Chemistry free + battle 1v1 →