medal will be awarded!! i really need help understanding this
Which of the following is an oxidation-reduction reaction?
a.)SO2(g) + H2O(l) mc010-1.jpg H2SO3(aq)
b.)CaCO3(s) mc010-2.jpg CaO(s) + CO2(g)
c.)Ca(OH)2(s) + H2CO3(l) mc010-3.jpg CaCO3(aq) + 2H2O(l)
d.)C6H12O6(s) + 6O2(g) mc010-4.jpg 6CO2(g) + 6H2O(l)

Question

medal will be awarded!! i really need help understanding this 
Which of the following is an oxidation-reduction reaction?
a.)SO2(g) + H2O(l)  mc010-1.jpg H2SO3(aq)
b.)CaCO3(s) mc010-2.jpg CaO(s) + CO2(g)
c.)Ca(OH)2(s) + H2CO3(l) mc010-3.jpg CaCO3(aq) + 2H2O(l)
d.)C6H12O6(s) + 6O2(g) mc010-4.jpg 6CO2(g) + 6H2O(l)

anonymous · Answer

Assign oxidation numbers and see which reaction has a change in the oxidation numbers.