In the reaction $2CHCl_3 + O_2 \xrightarrow{X} 2COCl_2 + 2HCl$,$X$ represents:

Product $(A)$ is :

Arrange the following compounds in order of decreasing rate of hydrolysis for $S_{N}1$ reaction:
$(I) \ C_6H_5-CH_2-Br$
$(II) \ p-CH_3-C_6H_4-CH_2-Br$
$(III) \ p-CH_3CH_2-C_6H_4-CH_2-Br$
$(IV) \ p-(CH_3)_2CH-C_6H_4-CH_2-Br$

Write a note on Wurtz Reaction.

Which of the following is most reactive for $SN^1$ reaction?

Enlist the main points of difference between $S_{N}1$ and $S_{N}2$ reactions.