The amount of solar radiation received anually in arizona is about 8.4 x 10^6 KJ/m^2. What mass of carbon must be burned into carbon dioxide to produce the same amount of energu in the following reaction?

C + 02 --->CO2 deltaH=-393.5Kj

It seems to me you must find the area of Arizona in square meters and multiply by 8.4 x 10^6 kJ/m^2 to find total energy. Then you know 12 g C will produce 393.5 kJ. Use proportion to find how many g C must be burned.