Theoretical basis of organic reactions

Write correct order of stability of following carbocations :

            

          

The most stable canonical structure of this molecule is:

In which of the following molecules / ions resonance structures are equivalent:

Among these compounds,  the correct order of C–N bond length is :

Rank the following free radicals in order of decreasing stability:

$\left(\text{I}\right){\text{C}}_6{\text{H}}_5\stackrel{•}{\text{C}}{\text{HC}}_6{\text{H}}_5$

$\left(\text{I}\text{I}\right){\text{C}}_6{\text{H}}_5\stackrel{•}{-\text{C}\text{H}}-\text{C}\text{H}={\text{C}\text{H}}_2$

$\left(\text{I}\text{I}\text{I}\right)\text{C}{\text{H}}_3\stackrel{•}{-\text{C}\text{H}}-\text{C}{\text{H}}_3$

$\left(\text{I}\text{V}\right){\text{C}}_6{\text{H}}_5\stackrel{•}{-\text{C}\text{H}}-\text{C}{\text{H}}_3$

$\left(\text{V}\right)\text{C}{\text{H}}_3{\text{CH}}_2{\text{CH}}_2{{\text{CH}}_2\stackrel{•}{\text{C}}\text{H}}_2$

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In which of the following pairs, is the first species is more stable than second?

In which of the following molecules π-electron density in ring is maximum ?

In which of the following molecules π-electron density in ring is minimum ?

Which of the following compounds has maximum electron density in ring ?

In phenol, π - electron - density is maximum on

The order of stability of these canonical forms is:

Among these canonical structures of pyridine, the correct order of stability is

The most stable resonating structure of following compound is

$\left(\mathrm{I}\right){\mathrm{CH}}_3-\mathrm{O}-\mathrm{CH}=\mathrm{CH}-{\mathrm{CH}=\mathrm{CH}}_2$

$\left(\mathrm{II}\right){\mathrm{CH}}_3-\mathrm{O}-\stackrel{\oplus }{\mathrm{C}}\mathrm{H}-\mathrm{CH}={\mathrm{CH}-\stackrel{\ominus }{\mathrm{C}}\mathrm{H}}_2$

$\left(\mathrm{III}\right){\mathrm{CH}}_3-\stackrel{\oplus }{\mathrm{O}}=\mathrm{CH}-\mathrm{CH}={\mathrm{CH}-\stackrel{\ominus }{\mathrm{C}}\mathrm{H}}_2$

Among these three canonical structures (through more are possible) what would be their relative contribution in the hybrid?

$\begin{array}{cc}\left(\text{I}\right)& {\text{CH}}_2=\underset{\updownarrow }{\text{C}}\text{H}-\text{CH}=\text{CH}-\text{O}{\text{CH}}_3\\ \left(\text{I}\text{I}\right)& \stackrel{\ominus }{\text{C}}{\text{H}}_2-\underset{\updownarrow }{\text{C}}\text{H}=\text{CH}-\text{CH}=\stackrel{\oplus }{\text{O}}{\text{CH}}_3\\ \left(\text{III}\right)& {\text{CH}}_2=\underset{\updownarrow }{\text{C}}\text{H}-\stackrel{\ominus }{\text{C}}\text{H}-\stackrel{\oplus }{\text{C}}\text{H}-\text{O}{\text{CH}}_3\\ \left(\text{IV}\right)& {\text{CH}}_2=\text{CH}-\stackrel{\oplus }{\text{C}}\text{H}-\stackrel{\ominus }{\text{C}}\text{H}-\text{O}{\text{CH}}_3\end{array}$

Among these canonical structures which one is least stable ?

In which of the following molecules - ${\text{NO}}_2$ group is not coplanar with phenyl ring?

In which of the following molecules resonance takes place through out the entire system

Hyperconjugation involves overlap of the following orbitals