Which of these changes produces the greatest
increase in entropy?
(1) caco3(s) --> cao(s) + co2(g)
(2) 2 mg(s) + o2(g) --> 2 mgo(s)
(3) h2o(g) --> h2o(l)
(4) co2(g) --> co2(s)

I think the correct answer is option 1. The reaction, CaCO3(s) --> CaO(s) + CO2(g), produces the greatest entropy since the products molecules are more disorganized than comparing it to the products of other choices. Entropy is the degree of disorderliness in a system.