Which of the following is most reactive towards electrophilic substitution?

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

Which of the following alkenes on treatment with $\mathrm{HBr}$in presence and absence of peroxide give the same product?

Dehydration of which of the following alcohols produce alkenes exhibiting cis-, trans- isomerism?