At constant pressure, which of these systems do work on the surroundings? Check all that apply.
2A (g) + B(s) --> 3C(g)
2A (g) +2B (g) -->5C(g)
A(g)+ B(g) --> C(g)
A (s) +2B(g)--> C(g)
I think the answer(s) is/are A and B.
A increases (note B is a solid) from 2 moles to 3 moles so that is an expansion. B is an expansion from 4 moles (2+2) to 5 moles C.
PLEASE confirm when you enter into the database. I like to make sure I'm right. ;-).