In which of the following reaction most stable enol is present.

Give the reactivity order towards $\mathrm{EAR}$.

Arrange the following in the correct order of reactivity towards ${\mathrm{Cl}}_2/\mathrm{h\nu }$:

$\left(\mathrm{A}\right)$ ${\mathrm{CH}}_4$
$\left(\mathrm{B}\right)$ ${\mathrm{CH}}_3{\mathrm{CH}}_3$
$\left(\mathrm{C}\right)$ ${\mathrm{CH}}_3{\mathrm{CH}}_2{\mathrm{CH}}_3$

$\left(\mathrm{D}\right)$ ${\mathrm{CH}}_3-\stackrel{\underset{|}{{\mathrm{CH}}_3}}{\mathrm{C}}\mathrm{H}-{\mathrm{CH}}_3$

The following equation repreasents a method of purification of nickel by :

$\mathrm{Ni} \left(\mathrm{impure}\right) + 4\mathrm{CO}\stackrel{320\mathrm{K}}{\to }\mathrm{Ni}(\mathrm{CO}{)}_4\stackrel{420\mathrm{K}}{\to }\mathrm{Ni} (\mathrm{pure}) + 4\mathrm{CO}$