Nitrating mixture is

The molecular formula of $3,4$-benzpyrene is ...... .

Which compound is formed when benzene is boiled with concentrated $HCl$?

Which compound amongst the following is not an aromatic compound?

Assertion : Benzene removes a butter stain from a table cloth.
Reason : Butter has an affinity towards benzene.

The order of decreasing reactivity towards an electrophilic reagent,for the following compounds,is:
$(i) \text{ Benzene} \quad (ii) \text{ Toluene} \quad (iii) \text{ Chlorobenzene} \quad (iv) \text{ Phenol}$