Identify the reagent (A) used in the following reaction.

What is the product formed when side chain chlorination of toluene is carried out followed by acid hydrolysis at $$373 \mathrm{~K}$$ ?

A system gives out $$\mathrm{x} \mathrm{~J}$$ of heat and does $$\mathrm{y} \mathrm{~J}$$ of work on it's surrounding. What is the internal energy change?

Which of following reactions yields biphenyl from chlorobenzene?