1: How many resonance structures does the carbonate ion (CO₃²⁻) have? Draw them and explain their stability.Answer:The carbonate ion (CO₃²⁻) has three resonance structures:Resonance Structures of CO₃²⁻:O=C=O <--> O⁻—C=O <--> O=C—O⁻Explanation:· In each structure, one of the oxygen atoms has a negative charge.· The actual structure of CO₃²⁻ is a resonance hybrid, meaning the negative charge is delocalized over all three oxygen atoms.· Since all resonance structures contribute equally, CO₃²⁻ has equivalent resonance structures.· This delocalization stabilizes the carbonate ion, making it more stable than a structure with localized charges.2: Draw and explain the resonance structures of benzene (C₆H₆).Answer:Benzene has two equivalent resonance structures:Resonance Structures of Benzene:The alternating single and double bonds shift positions.Explanation:· The actual structure of benzene is a resonance hybrid of these two forms.· Instead of single and double bonds, benzene has delocalized π-electrons across all six carbon atoms.· This delocalization makes benzene exceptionally stable, which is why it is classified as an aromatic compound.3: Which of the following is the most stable resonance structure?(A) A structure with full octets, minimal charge separation(B) A structure with charge separation and incomplete octets(C) A structure with a negative charge on the less electronegative atom(D) A structure with a positive charge on oxygen and a negative charge on carbonCorrect Answer:(A) A structure with full octets and minimal charge separation.Explanation:· The most stable resonance contributor is the one that obeys the octet rule, has minimal charge separation, and places negative charges on more electronegative atoms (e.g., oxygen rather than carbon).· The least stable structure is one where there are unfavorable charges, such as a positive charge on oxygen or a negative charge on carbon.4: Draw the resonance structures of the acetate ion (CH₃COO⁻) and explain their stability.Answer:The acetate ion (CH₃COO⁻) has two resonance structures:Resonance Structures of Acetate Ion (CH₃COO⁻):Explanation:· The negative charge is delocalized between the two oxygen atoms.· This equal distribution of charge makes acetate more stable than a structure where the charge is fixed on one oxygen.· Since both oxygen atoms contribute equally, both resonance forms are equivalent.5: Which of the following compounds has the most delocalized electrons?a) NH₃b) CO₂c) O₃d) CH₄Correct Answer:c) O₃ (Ozone)Explanation:· Ozone (O₃) has two resonance structures, where the double bond shifts between the two oxygen atoms.· This delocalization of π-electrons makes O₃ more stable than a single Lewis structure.· CO₂ does not have resonance because it already has a stable linear structure with full octets.6: Why is the allyl cation (C₃H₅⁺) more stable than a simple carbocation? Draw its resonance structures.Answer:The allyl cation (C₃H₅⁺) has two resonance structures:CH₂=CH—CH₂⁺ <--> CH₂⁺—CH=CH₂Explanation:· The positive charge is delocalized over two carbon atoms, making the allyl cation more stable than a localized carbocation.· This resonance stabilization makes the allyl cation more reactive but still more stable than a simple primary carbocation.7: How many resonance structures does the nitrite ion (NO₂⁻) have? Draw them.Answer:The nitrite ion (NO₂⁻) has two resonance structures:Explanation:· The negative charge is delocalized over the two oxygen atoms.· This spreads the charge evenly, increasing the ion’s stability.· Since both structures contribute equally, they make NO₂⁻ more stable than a single Lewis structure.8: True or False – All resonance structures must have the same number of valence electrons.Answer:TrueExplanation:· Electrons cannot be created or destroyed only rearranged.· The number of valence electrons remains constant across all resonance structures.9: How many resonance structures does the nitrate ion (NO₃⁻) have?a) 1b) 2c) 3d) 4Answer: (c) 3Explanation: The nitrate ion (NO₃⁻) has three equivalent resonance structures where the double bond moves among the three oxygen atoms, delocalizing the negative charge.10: In the resonance hybrid of the formate ion (HCOO⁻), which atoms bear partial charges?a.) Both oxygen atomsb.) Carbon and one oxygenc.) Only one oxygend.) Hydrogen and oxygenAnswer: (a) Both oxygen atomsExplanation: The negative charge is delocalized over both oxygen atoms in the resonance hybrid, so each oxygen carries a partial negative charge.11: Which of the following criteria makes a resonance form the most important contributor?a.) The structure with the least charge separationb.) The structure that follows the octet rulec.) The structure where the negative charge is on the most electronegative atomd.) All of the aboveAnswer: (d) All of the aboveExplanation: The most stable resonance form is the one that:· Minimizes charge separation· Follows the octet rule· Places negative charges on electronegative atoms like oxygen.12. Which of the following molecules shows resonance stabilization?a) Benzyl carbocation (C₆H₅CH₂⁺)b) Ethyl carbocation (C₂H₅⁺)c) Methyl carbocation (CH₃⁺)d) Tertiary carbocation (CH₃C⁺(CH₃)₂)Answer: (a.) Benzyl carbocation (C₆H₅CH₂⁺)Explanation: The benzyl carbocation is highly stable because the positive charge is delocalized across the benzene ring through resonance.13. Which of the following carbo-cations is the most stable due to resonance?a.) CH₃⁺ (methyl carbocation)b.) CH₃CH₂⁺ (ethyl carbocation)c.) C₆H₅CH₂⁺ (benzyl carbocation)d.) CH₃C⁺(CH₃)₂ (tertiary carbocation)Answer: (c) C₆H₅CH₂⁺ (benzyl carbocation)Explanation: The benzyl carbocation is resonance-stabilized because the positive charge moves around the benzene ring, increasing stability.14: How does hyper-conjugation contribute to the stability of the allyl cation (CH₂=CH—CH₂⁺)?a.) By moving the positive charge onto oxygenb.) By allowing the p-orbitals to overlap, spreading out the chargec.) By localizing the charge on one carbon atomd.) By removing electrons from the systemAnswer: (b.) By allowing the p-orbitals to overlap, spreading out the chargeExplanation: The allyl cation is resonance stabilized because the positive charge is delocalized over two carbon atoms through p-orbital overlap.15: Which of the following resonance structures is the least stable?a.) A structure where all atoms obey the octet ruleb.) A structure where a positive charge is placed on an oxygen atomc.) A structure where the negative charge is on a carbon atom instead of an oxygen atomd.) A structure with minimal charge separationAnswer: (b.) A structure where a positive charge is placed on an oxygen atomExplanation: Oxygen is highly electronegative, so it does not stabilize a positive charge well. Such structures contribute less to the resonance hybrid.16: Resonance structures are different isomers of a compound.a.) Trueb.) FalseAnswer: (b) FalseExplanation: Resonance structures are not isomers, they are different ways of representing electron delocalization in the same molecule.17: Which of the following compounds has equally stable resonance structures?a.) Phenoxide ion (C₆H₅O⁻)b.) Carbonate ion (CO₃²⁻)c.) Acetate ion (CH₃COO⁻)d.) All of the aboveAnswer: (d) All of the aboveExplanation: In all these ions, resonance delocalizes the negative charge equally among oxygen atoms, leading to equivalent resonance structures.18. Which of the following does not exhibit resonance?a.) O₃ (ozone)b.) NH₃ (ammonia)c.) NO₂⁻ (nitrite ion)d.) CH₃COO⁻ (acetate ion)Answer: (b) NH₃ (ammonia)Explanation: Ammonia (NH₃) does not have delocalized electrons and has a fixed lone pair on nitrogen, meaning it does not show resonance.