Presence of nitro group in a benzene ring

The major product obtained on monochlorination $({\mathrm{Br}}_2/{\mathrm{FeBr}}_3)$ of the following compound A is

Identify the compound $\mathrm{B}$ formed.

Among the following compounds, the decreasing order of reactivity towards electrophilic substitution is

The order of decreasing reactivity towards an electrophilic reagent for the following:

i) Benzene       ii) Toluene         iii) Chlorobenzoic acid           iv) Phenol   

would be.