Resonance Effect

Q.

In pyrrole

the electron density is maximum on

1. 2 and 3

2. 3 and 4

3. 2 and 4

4. 2 and 5

Q. The correct stability order of the following resonance structures is:

1. (I) > (II) > (IV) > (III)
2. (I) > (III) > (II) > (IV)
3. (II) > (I) > (III) > (IV)
4. (III) > (I) > (IV) > (II)

Q. Which of the following resonating structures of 1-methoxy-1, 3-butadiene is least stable?

1. $\stackrel{\ominus }{C}{H}_2-CH=CH-CH=\stackrel{\oplus }{O}-C{H}_3$
2. $C{H}_2=CH-\stackrel{\ominus }{C}H-CH=\stackrel{\oplus }{O}-C{H}_3$
3. $\stackrel{\ominus }{C}{H}_2-\stackrel{\oplus }{C}H-CH=CH-O-C{H}_3$
4. $C{H}_2=CH-\stackrel{\ominus }{C}H-\stackrel{\oplus }{C}H-O-C{H}_3$

Q.

Predict the number of unpaired electrons in the square planar [Pt(CN)₄]²⁻ ion.

Q.

What is resonance energy?

Q.

Amongst $Ni(CO{)}_4,[Ni(CN{)}_4{]}^{2-}andNiC{l}_4^{2-}:$

1. $Ni(CO{)}_{4}andNiC{l}_4^{2-}$ are diamagnetic; and $\left[Ni\right(CN{)}_4{]}^{2-}$ is paramagnetic.

2. $Ni\left(CO{)}_{4}and\right[Ni(CN{)}_4{]}^{2-}$ are diamagnetic; and $NiC{l}_4^{2-}$ is paramagnetic.

3. $\left[Ni\right(CN{)}_4{]}^{2-}andNiC{l}_4^{2-}$ are diamagnetic; and $Ni(CO{)}_4$ is paramagnetic.

4. $Ni(CO{)}_{4}isdiamagnetic;[Ni(CN{)}_4{]}^{2-}$ and $NiC{l}_4^{2-}$ is paramagnetic.

Q. Maximum extent of steric inhibition of resonance can be expected in

1. 
2. 
3. 
4. 

Q.

Resonating structure of ${\mathrm{SO}}_3$?

Q. While considering double and triple bond which should be given preference for numbering

Q. For thiocyanate ion ($SC{N}^{-}$), three resonating structures are possible with the electron-dot method as shown below:

The decreasing order of $\%$ contribution to the resonance hybrid is:

1. Cannot be predicted
2. $a>c>b$
3. $a>b>c$
4. $c>b>a$

Q. The possible number of resonating structures for the anthracene molecule are:

1. 2
2. 3
3. Resonance not possible
4. 4

Q. Which of the following is the correct order of the dominating power of the given effects on the stability of intermediates?
I. Resonance effect II. Hyperconjugation
III. Inductive effect IV. Aromaticity

1. III > II > IV > I
2. IV > I > II > III
3. IV > II > III > I
4. I > IV > III > II

Q. Which of the following resonating structure of napthalene is the most stable?

1. $I$
2. $II$
3. $III$
4. All are equally stable.

Q.

Which of the following has zero dipole moment?

1. $\mathrm{ClF}$

2. ${\mathrm{PCl}}_3$

3. ${\mathrm{SiF}}_4$

4. ${\mathrm{CFCl}}_3$

Q.

Which is more stable resonance or hyperconjugation?

Q. The resonance energy is defined as a difference in energy between

1. Two consecutive resonating structures
2. Resonance hybrid and most unstable resonating structure
3. Resonance hybrid and most stable resonating structure
4. First and last resonating structures

Q.

Write the mechanism of the following reaction.

$nBuBr+KCN\stackrel{EiOH-H_{2}O}{\to }nBuCN$

Write the resonating structures of KCN.

Due to the presence of polar solvent, find the possiblity, which product will be formed preferentially ?

Q.
The most stable resonating structure among the given structures is :

1. $I$
2. $II$
3. $III$
4. All are equally stable.

Q.

What is meta Directing effect?

Q. Select the correct statement about this compound.

1. All three C - N bond length are same.
2. $C_1-N$ and $C_3-N$ bonds length are same but shorter than $C_5-N$ bonds length.
3. $C_1-N$ and $C_5-N$ bonds length are same but longer than $C_3-N$ bond length.
4. $C_1-N$ and $C_3-N$ bonds length are different but both are longer than $C_5-N$ bond length.

Q.

Which one is the most reactive towards an electrophilic reagent?

1. 

2. 

3. 

4. 

Q.

What is an alkoxide? Give an example.

Q.

Formation of Cl^- is exothermic but formation of O^2- is endothermic . Explain

Q. Which will be the least stable resonating structure?

1. 
2. 
3. 
4. 

Q.

How would you account for the following:

(i) Of the d⁴species, Cr²⁺ is strongly reducing while manganese(III) is strongly oxidising.

(ii) Cobalt(II) is stable in aqueous solution but in the presence of complexing reagents it is easily oxidised.

(iii) The d¹ configuration is very unstable in ions.

Q. Which of the following reagents may be used to distinguish between phenol and benzoic acid?

1. Molisch reagent
2. Neutral $FeC{l}_3$
3. Aqueous NaOH
4. Tollen’s reagent

Q. Resonance structure of molecule does not have

1. Identical bonding
2. Identical arrangement of atoms
3. Nearly the same energy content
4. The same number of paired electrons

Q. Which of the following is/are the neccessary conditions for resonance?

1. The position of all the atomic nuclei in the resonating structures are not the same
2. Conjugated system
3. Each resonating structure should have same number of paired and unpaired electrons
4. Interconvertible lone pairs and bond pairs.

Q. Number of resonating structures of aniline is:

Q. The number of resonating structures of chlorobenzene are :