Balance the following oxidation-reduction reactions, which occur in acidic solution, using the half-reaction method. (Use the lowest possible coefficients.

Question

(a) H2O2(l) + Pb(s) → H2O(l) + Pb2+(aq)
(b) O2(g) + Mn(s) → H2O(l) + Mn2+(aq)

Answer 1

Here is a site that provide a lot of information on the redox equations including the half rxn method.
http://www.chemteam.info/Redox/Redox.html

I shall be happy to answer in specific questions you have to help get you started.
The half rxns for #1 are
H2O2 ==> H2O and
Pb ==> Pb^2+