Final answer:
A feed stream containing btuan and a feed stream containing air are fed into a reactor. So, the correct answer is option 1) a reactor.
Step-by-step explanation:
A feed stream containing btuan (assuming 'butane' was the intended term) and air can have different purposes depending on the process; however, given the context of potential processes, the most likely place where a hydrocarbon like butane and air would be fed into is a reactor, as options such as a distillation column or a heat exchanger do not typically involve the direct feeding of air into the system for chemical reactions.
Instead, a reactor is the piece of equipment where chemical reactions between substances like hydrocarbons and air are conducted to produce different chemicals or products through processes such as combustion or oxidation.
According to the options provided, the correct answer is 1) a reactor.