Topic Question Set
Q 1
:
The correct stability order of carbocation is [2024]
(3)
Stability of carbocations follows the order: 3° > 2° > 1°. This is due to more hyperconjugation and +I stability in higher degree carbocations.
Q 2
:
A species having carbon with sextet of electrons and can act as electrophile is called [2024]
pentavalent carbon
carbon free radical
carbocation
carbanion
(3)
Carbon can form maximum of four bond. There is nothing called pentavalent carbon.
Q 3
:
Correct order of stability of carbanion is [2024]
d > a > c > b
d > c > b > a
a > b > c > d
c > b > d > a
(2)
Q 4
:
The shape of carbocation is: [2024]
tetrahedral
trigonal planar
diagonal pyramidal
diagonal
(2)
Q 5
:
Number of carbocation from the following that are not stabilized by hyperconjugation is………. [2024]
(5)
For hyperconjugation to occur in carbocations, carbon carrying positive charge should be connected to an hybridized carbon and that hybridized carbon should have at least one H atom (called as H).
Out of given seven structures, hyperconjugation is possible only in the following two structures:
Q 6
:
Which one of the carbocations from the following is most stable? [2025]
(3)
+M groups stabilize a carbocation by supplying electrons. Order of +M effect is:
Q 7
:
The correct order of stability of following carbocations is: [2025]
C > A > B > D
B > C > A > D
C > B > A > D
A > B > C > D
(1)
Q 8
:
Which among the following halides will generate the most stable carbocation in the nucleophilic substitution reaction? [2025]
(4)
Carbocation formed by (4) is stabilized by +M effect of three Ph groups hence is most stable in the given options. Stability order of carbocations is:
Q 9
:
The most stable carbocation from the following is: [2025]
(2)
Electron donating groups increase stability of a carbocation. –OMe group can donate electrons by +M effect from ortho and para position. +M effect of –OMe dominates over its – effect. From meta position it withdraws electron density because of – effect. Electron donation by +M effect of –OMe is more than the electron donation by hyperconjugation and + effect of – group.
Q 10
:
The correct stability order of the following species/molecules is: [2025]
(3)
Cyclooctatetraene adopts non planar tub shaped structure to avoid anti aromaticity. So it is non aromatic. Thus stability order of given compounds is:
q (aromatic) > r (non aromatic) > p (anti aromatic)
