Explain what accounts for the variable oxidation states, complete ions and colours of transition elements.

Oxygen= 88ghydrogen= 12g

Bromine has atomic number  35  which means there are  35 protons  and  44  neutrons to give a total of 79 nucleons. the fact that it's a positive ion means that it has lost an electron; so there'll be  34 electrons. 

Where? we need more.

Pcl5 + 4 h2o = h3po4 + 5 hclthe ratio is 1: 5 for  pcl  and hcl, 1 mole of pcl produces 5 moles of hclmolecular weight of pcl5 is: 31 + (5 x 35.5) = 208.5above we have 75.5 / 208.5 = 0.36 moles so this will produce0.36 x 5 = 1.81 moles of hcl.