Which can be considered a system?

A system is a collection of elements or components that are organized for a common purpose. ... All of nature and the universe can be said to be a system. We've coined a word, ecosystem, for the systems on Earth that affect life systems. The term can be very useful because so many things can be described as systems.

> b takes place in the gas phase in an isothermal tubular reactor. the feed is one mole of a per one mole of c, an inert. the entering temperature and pressure are 427°c and 10 atm, respectively. the gas constant r = 0.08206 atm · l/mol · k.