Oxygen is 21% and nitrogen is 78% so combined is 99%
<u>Answer:</u>
<em>The system is the Answer
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<u>Explanation:</u>
System is the region which is taken into consideration.
While we perform a chemical reaction the system is the substance taken in the container.
So, A thermodynamic system is the amount of matter or the region in universe which is under the study.
The region outside the beaker are called as surroundings.
The beaker (the surface which separates the system from its surroundings) is said to be the boundary
System + surroundings = universe
B. 538 j hoped this helps