The part of the system that is designated as surroundings is;
Inside the fume hood
We are told that the chemist is performing a reaction under a fume hood.
Now, in thermodynamics there is what we call homogenous and heterogenous systems. Each of those systems have what we call surroundings, system and boundary.
Now, everything that is around a system is referred to as a surrounding while boundary is simply defined as everything that is external to the system.
Now, in this case since the chemist is performing the chemical reaction under a fume hood, then the boundary will be everything outside the fume hood while the surroundings will be inside the fume hood.
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