Question

Which two of these are redox reactions?

a) MnO_2 + 4HCl → MnCl_2 + 2H_2O + Cl_2
b) CaCO₃ + 2HCl → CaCl₂ + H₂O + CO₂
c) NH₃ + HCl → NH₄Cl
d) 2H₂O₂ → 2H₂O + O₂
e) 2NaOH + H₂SO₄ → Na₂SO₄ + 2H₂O
f) CO₂ + CaO → CaCO₃

a) a, b
b) b, c
c) c, d
d) e, f

Answer 1

The redox reactions are a) MnO2 + 4HCl → MnCl2 + 2H2O + Cl2 and d) 2H2O2 → 2H2O + O2.

Step-by-step explanation:

Redox reactions involve the transfer of electrons from one reactant to another. Looking at the given options:

a) MnO2 + 4HCl → MnCl2 + 2H2O + Cl2

d) 2H2O2 → 2H2O + O2

These two reactions are redox reactions because the oxidation state of the elements involved changes. In option a), Mn in MnO2 is reduced from +4 to +2, while Cl in HCl is oxidized from -1 to 0. In option d), H in H2O2 is oxidized from -1 to 0, and O in O2 is reduced from 0 to -2.