The net ionic equation: Fe(s) + Pb2+ (aq) – Fe2+ (aq) + Pb(s) illustrates conservation of 1.
mass and charge
2.
charge but not mass
3.
mass but not charge
4.
neither mass nor charge

Rate law for this reaction israte of the reaction = k[a]²[b].second order in a  means concentration of a in power of two, and  first order in b means concentration of b in power of one.

D. h2o + h2o > h3o + oh- confirmed.

Visible light is located in the middle of the spectrum.