NEET UG 2018 — Chemistry Organic Chemistry

2018mcqmedium

Which of the following carbocations is expected to be the most stable?

Official previous-year question

Held on 30 Apr 2018 · Verified 9 Jul 2026.

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Solution

${\mathrm{NO}}_{2}$ is present at the ortho- and the para- position of a positive charge.

${\mathrm{NO}}_{2}$ present at the meta-position of a positive charge is less stable due to the ${e}^{-}$ withdrawing effect of $-{\mathrm{NO}}_{2}$ ( $-I$ effect of ${\mathrm{NO}}_{2}$ )

NEET 2018 Chemistry, General Organic Chemistry — solution figure 1

${\mathrm{NO}}_{2}$ present at the ortho- and para- of positive charge (Less stable due to the ${e}^{-}$ withdrawing effect of $-{\mathrm{NO}}_{2}$ ( $-M$ effect.)

NEET 2018 Chemistry, General Organic Chemistry — solution figure 2

The positive charge is destabilized by the electron-withdrawing groups.

$-M$ dominates $-I$ effect. So, the carbocation which has $-I$ group is more stable.

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NEET UG 2018 — Chemistry Organic Chemistry

2018mcqmedium

Which of the following carbocations is expected to be the most stable?

Official previous-year question

Held on 30 Apr 2018 · Verified 9 Jul 2026.

Options

Did you get this right?

Solution

${\mathrm{NO}}_{2}$ is present at the ortho- and the para- position of a positive charge.

${\mathrm{NO}}_{2}$ present at the meta-position of a positive charge is less stable due to the ${e}^{-}$ withdrawing effect of $-{\mathrm{NO}}_{2}$ ( $-I$ effect of ${\mathrm{NO}}_{2}$ )

NEET 2018 Chemistry, General Organic Chemistry — solution figure 1

${\mathrm{NO}}_{2}$ present at the ortho- and para- of positive charge (Less stable due to the ${e}^{-}$ withdrawing effect of $-{\mathrm{NO}}_{2}$ ( $-M$ effect.)

NEET 2018 Chemistry, General Organic Chemistry — solution figure 2

The positive charge is destabilized by the electron-withdrawing groups.

$-M$ dominates $-I$ effect. So, the carbocation which has $-I$ group is more stable.

NEET UG 2018 — Chemistry Organic Chemistry

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Solution

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NEET UG Organic Chemistry in other years

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Physical Chemistry

Inorganic Chemistry

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NEET UG 2018 — Chemistry Organic Chemistry

Options

Did you get this right?

Solution

Your note

NEET UG Organic Chemistry in other years

More NEET UG Organic Chemistry questions

Other Chemistry topics for NEET UG

Physical Chemistry

Inorganic Chemistry

Keep practicing Organic Chemistry