Question

Which of the following reactions does not involve oxidation-reduction?

a). C3H8 + 5O2 → 4H2O + 3CO2
b). Mg + 2HI → MgI2 + H2
c). Ba + 2H2O → Ba(OH)2 + H2
d). MnO2 + 4HI → I2 + 2H2O + MnI2
e). NaOH + HI → H2O + NaI

Answer 1

The point of this you missed. You should be able to look at them and see which ones changed oxidation state.
c for example, Ba is zero, goes to +2
d for example, Mn goes from +4 to +2

One of the equations oxdation states do not change.