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.

The ease of nitration of the following three hydrocarbons follows the order

Electrophilic substitution of compound A will be fastest at position _____

In the Newman projection for $2,2$-dimethylbutane

X and Y can respectively be