At constant temperature and pressure, 5.0 l of so2 is
combined with 3.0 l of o2 according to the equation:
2 so2(g) + o2(g)  2 so3(g)
after so3 formation is complete, what is the volume of
the mixture?
(a) 5.5 l (b) 6.0 l (c) 6

I've done this a few times and keep coming up with 5.0 L . I used the mole ratio, and SO 2 as the LR. That would make 2 moles of SO3 5.0 L but its not one of your choices. the temp and pressure are constant, so according to n/v = p/rt the volume is the same as the moles. hope this helps

Coal i believe hope this