An incorrect statement with respect to ${\text{S}}_{\text{N}}1$ and ${\text{S}}_{\text{N}}2$ mechanism for alkyl halide is

The increasing order of reactivity of the following compounds towards reaction with alkyl halides directly is:

$\left(i\right)$

$\left(ii\right)$

$\left(iii\right)$

$\left(iv\right)$

The major product of the following reaction is:

The major product of the following reaction is:

The reagent required for the following two step transformation are

The major product of the following reaction is: