Among the following reaction(s), which gives(give) tert-butyl benzene as the major product is(are)

Reagent(s) which can be used to bring about the following transformation is(are)

The nitrogen containing compound produced in the reaction of HNO₃ with P₄O₁₀

Treatment of compound O with KMnO₄/H⁺ gave P, which on heating with ammonia gave Q. The compound Q on treatment with Br₂/NaOH produced R. On strong heating, Q gave S, which on further treatment with ethyl 2-bromopropanoate in the presence of KOH following by acidification, gave a compound T.

The compound R is