The answer is gonna be the last one :)
The 5 main branches of chemistry are physics, analytical, biochemistry, organic chemistry, and inorganic chemistry.
Lead is an E (element) and can be found on the periodic table.
Take 46g / 46 g/mol = 1 mol NO2 produced
1 mol * 1/2 = 0.5 mol O2 needed (1/2 ratio between NO2 and O2)
