Which of the following redox reactions do you expect to occur spontaneously in the forward direction under standard conditions?

a. Ni(s)+Zn2+(aq)→Ni2+(aq)+Zn(s)
b. Pb(s)+Mn2+(aq)→Pb2+(aq)+Mn(s)
c. Ni(s)+Pb2+(aq)→Ni2+(aq)+Pb(s)
d. Cr(s)+3Ag+(aq)→Cr3+(aq)+3Ag(s)
e. None of the above

b. spontaneous.

c. spontaneous.

Explanation:

Using the net standard potential, it is possible to determine if the reaction is spontaneous or not.  If the standard potential of the reaction is positive, the reaction is spontaneous, whereas if the standard potential of the reaction is negative, the reaction is non-spontaneous.

a. Ni(s)+Zn2+(aq)→Ni2+(aq)+Zn(s)  E° = - 0.53 v

b. Pb(s)+Mn2+(aq)→Pb2+(aq)+Mn(s)  E° = + 0.10 v

c. Ni(s)+Pb2+(aq)→Ni2+(aq)+Pb(s)  E° = + 2.46 v

d. Cr(s)+3Ag+(aq)→Cr3+(aq)+3Ag(s) E° = - 1.05 v

2h2o2--> 2h2o + o2

this reaction is of the spontaneous decomposition of hydrogen peroxide down into water and oxygen.

add 2 molecules of hydrogen peroxide and 2 molecules of water. since oxygen is naturally diatomic, the total number of atoms of each element is now the same on both sides of the equation so it is balanced.

this may not be entirely correct but let me know.