Do the same for halogenation of an alkene -- as review. Now we do not have HBr as a product. Explain why not -- in terms of balancing the reaction, especially from the standpoint of H atoms.
CH2=CH2 + y Br2 - - - > dibromo-ethane
Write this out with structures and with the correct value of y. Note that there are 2 possible products -- different compounds. So, in answering this part of the question -- about synthesis of the dibromo-ethane -- actually write two separate reactions, each producing one of the 2 possible different products.