Homolytic and heterolytic fission; radicals, carbocations and carbanions — NEET & JEE Questions

Question 1 · difficulty L1 · recall

What is formed when a covalent bond undergoes homolytic fission?

• A. Two free radicals, each receiving one bonding electron
• B. A carbocation and a carbanion
• C. Two cations
• D. Two anions

Question 2 · difficulty L2 · understanding

What distinguishes heterolytic fission from homolytic fission?

• A. In heterolytic fission each atom gets one electron
• B. In heterolytic fission one atom receives both bonding electrons
• C. Heterolytic fission never produces charged species
• D. Heterolytic fission can occur only in non-polar bonds

Question 3 · difficulty L2 · understanding

Which species is a carbocation?

• A. $CH_3^+$
• B. $CH_3^-$
• C. $CH_3\cdot$
• D. $CH_4$

Question 4 · difficulty L2 · understanding

Which statement about a carbanion is correct?

• A. It is electron-deficient and positively charged
• B. It contains a negatively charged carbon with a lone pair
• C. It contains an unpaired electron but no charge
• D. It is always electrically neutral

Question 5 · difficulty L3 · application

Homolytic cleavage of the C–Cl bond in $CH_3Cl$ would produce which pair of species?

• A. $CH_3^+$ and $Cl^-$
• B. $CH_3^-$ and $Cl^+$
• C. $CH_3\cdot$ and $Cl\cdot$
• D. $CH_4$ and $Cl^-$

Question 6 · difficulty L3 · application

If the C–Br bond in $CH_3Br$ breaks heterolytically with both bonding electrons going to bromine, which products form?

• A. $CH_3^+$ and $Br^-$
• B. $CH_3^-$ and $Br^+$
• C. $CH_3\cdot$ and $Br\cdot$
• D. $CH_4$ and $Br^+$

Question 7 · difficulty L3 · application

Which carbocation is expected to be the most stable among the following simple alkyl carbocations?

• A. Methyl carbocation
• B. Primary carbocation
• C. Secondary carbocation
• D. Tertiary carbocation

Question 8 · difficulty L3 · application

Among methyl, primary, secondary and tertiary simple alkyl carbanions, which is generally the most stable?

• A. Methyl carbanion
• B. Primary carbanion
• C. Secondary carbanion
• D. Tertiary carbanion

Question 9 · difficulty L4 · application

Which pairing of bond fission and product type is correct?

• A. Homolytic fission → ions; heterolytic fission → radicals
• B. Homolytic fission → radicals; heterolytic fission → ions
• C. Both types always give radicals
• D. Both types always give ions

Question 10 · difficulty L4 · application

A carbon–halogen bond undergoes heterolytic cleavage. Which factor most directly determines which atom takes the bonding electron pair?

• A. The more electronegative atom is generally favored to take the pair
• B. The less electronegative atom must always take the pair
• C. The larger atom must always become positive
• D. The atom with fewer neutrons takes both electrons