if the pressure during the reaction stays CONSTAT (put the valune can change, like in a piston balloon which of these reactions do work on the surroundings?
1) A(s)+B(g)-->C(g)
2) A(g)+B(g)-->C(s)
3) A(s)+B(aq)-->2C(g)
4) A(g)+B(g)-->3C(g)
5) A(s)+B(g)-->2C(g)
6) A(g)+B(s)-->C(s)+D(g)