Acetylene on reaction with 1 mol of HCl in the presence of mercuric chloride produces

When acetylene reacts with hydrochloric acid in presence of mercuric chloride, the product obtained is :

Acetylene reacts with nitrogen in the presence of electric spark to produce

An organic compound A (C_8H_6) reacts with dilute H_2SO_4 in presence of mercuric chloride to produce another compound (B) . B is also obtained when benzene reacts with an acid chloride in presence of anhyd. AlCl_3 . Identify A and B and give the reactions involved.

But-1-ene on reaction with HCl in the presence of benzoyl peroxide yields-

Acetylene is allowed to react with an excess of HCl in the presence of HgCl_2 . The product formed is