Total number of $2°$ amine isomers of ${\mathrm{C}}_4{\mathrm{H}}_{11}\mathrm{N}$ would be (only structural)

Show the direction of inductive effect in following compounds:

$\left(1\right)$   $\left(2\right)$ 

$\left(3\right)$ ${\mathrm{CH}}_3-\mathrm{CH}={\mathrm{CH}}_2$        $\left(4\right)$ ${\mathrm{CH}}_3-{\mathrm{CH}}_2-{\mathrm{CH}}_2-\mathrm{Li}$  

$\left(5\right)$ ${\mathrm{CH}}_3-{\mathrm{CH}}_2-{\mathrm{CH}}_2-\mathrm{MgBr}$     $\left(6\right)$ ${\mathrm{CH}}_3-{\mathrm{CH}}_2-\mathrm{OH}$

$\left(7\right)$    $\left(8\right)$   

 $\left(9\right)$    $\left(10\right)$ 

Which of the following compounds have delocalised electrons?

$\left(\mathrm{P}\right)$ 

$\left(\mathrm{Q}\right)$ 

$\left(\mathrm{R}\right)$ 

$\left(\mathrm{S}\right) {\mathrm{CH}}_3{\mathrm{CH}}_2\mathrm{NHCH}={\mathrm{CHCH}}_3$

The number of $\mathrm{\pi }$ electrons in resonance in the following structure:

In the following sets of resonating structures, label the major and minor contributors towards resonance hybrid.

$\left(\mathrm{P}\right)$ 

$\left(\mathrm{Q}\right)$ 

$\left(\mathrm{R}\right)$ 

$\left(\mathrm{S}\right)$ 

Write the stability order of the following resonating structures:

$\left(\mathrm{P}\right)$    $\left(\mathrm{Q}\right)$  

$\left(\mathrm{R}\right)$    $\left(\mathrm{S}\right)$