When chloroform is treated with excess oxygen,it forms:

The major product of the reaction between $CH_{3}CH_{2}ONa$ and $(CH_{3})_{3}CCl$ in ethanol is

In the following reaction sequence,the correct structure$(s)$ of $X$ is (are)
$X$ $\xrightarrow[2) NaI, Me_2CO]{1) PBr_3, Et_2O}$ $\xrightarrow{3) NaN_3, HCONMe_2} \text{enantiomerically pure product}$

What is the correct order of leaving group ability for the following groups?
$I. -OAc$
$II. -OMe$
$III. -OSO_2Me$
$IV. -OSO_2CF_3$

Which of the following reactants is used to obtain the compound $(A)$ shown below? (Assume that $EtO^{-}$ is used in all the reactions)

Which of the following is most reactive towards ${S_N}^2$ reaction?