In an ${\mathrm{S}}_{\mathrm{N}}1$ reaction, the configuration of the product undergoes:

Following reaction is:

The major product obtained on the mono-bromination (with ${\mathrm{Br}}_2/{\mathrm{FeBr}}_3$) of the following compound $\mathrm{A}$ is:

The correct increasing order of reactivity for the following molecules towards electrophilic aromatic substitution is:

Assertion $\left(\mathrm{A}\right)$ : Presence of nitro group facilitates nucleophlic substitution reactions in aryl halides.

Reason $\left(\mathrm{R}\right)$ : The intermediate carbocation is stable due to presence of nitro group.    

$\mathrm{IUPAC}$ name of

is: