Write a balanced chemical equation for each of the following reactions:
a. Dinitrogen pentoxide reacts with sodium metal to produce sodium nitrate and nitrogen dioxide.
b. A mixture of nitric acid and nitrous acid is formed when water reacts with dinitrogen tetroxide.
c. At high pressure, nitrogen monoxide decomposes to dinitrogen monoxide and nitrogen dioxide.
d. Acetylene, $mathrm{C}_{2} mathrm{H}_{2},$ burns and becomes carbon dioxide and water vapor.