Which one of the following is a redox reaction?

Al3+(aq) + PO43-(aq) → AlPO4(s)
NaCl(aq)+ AgNO3(aq) NaNO3(aq)+ AgCl(s)
3Mg(s) + 2FeCl3(aq) → 3 MgCl2(aq) + 2Fe(s)
LiCl(aq) + AgCH3CO2(aq) → AgCl(aq) + LiCH3CO2(aq)
HF(aq) + KOH(aq) → H2O(ℓ) + KF(aq)

What is the overall order of reaction for rate = k[no]2[o2]

The bond energy for the van der waals bond between two helium atoms is 7.9×10−4ev. assuming that the average kinetic energy of a helium atom is (3/2)kbt, at what temperature is the average kinetic energy equal to the bond energy between two helium atoms

How might this scientific phenomena be explained? a paper clip floats on water.