Carbon dioxide can be obtained by which of the following methods?

a. Heating uranium ore
b. Combustion of natural gas
c. Fractional distillation of liquid air
d. Oxidizing ammonia at high temperatures

ANS: B
Unrefined carbon dioxide can be obtained from the combustion of coal, natural gas, or other carbonaceous fuels. Helium can be obtained by heating uranium ore. The two methods most commonly used to prepare oxygen are the fractional distillation of liquid air and the physical sep-aration of atmospheric air. Nitric oxide can be prepared by oxidizing ammonia at high tempera-tures (i.e., 500? C and above).