Ducky

Yeah, open book is very difficult, but i nearly got it! In answer to your question jellybaby "In the 1st equation of the original post, is the O meant to be a radical? If yes, where does it come from [only explanation i can find is the breakdown of NO2?] and if not, how is it just an O on its own??" it comes from the second step, it produces a 'bi radical', that is when there is 2 radicals in the 1 atom, and the O=N so it would look like, . : + O=N ' Radicals, being at the top and bottom of this, that is going into Degree level chem. FUN!!! Hope this helps!! Good luck!!!