Statement number (2) is correct,
Standard electrode potentials are used to express the ability of a substance to lose electrons.
When you compare the
Here's a link to a table of Standard Electrode Potentials: http://hyperphysics.phy-astr.gsu.edu/hbase/tables/electpot.html
Any species that appears on the left of the reduction half-reaction will oxidize any species that appears on the right of a reduction half-reaction listed above it in the table.
Likewise, any species that appears on the right of the reduction half-reaction will reduce any species that appears on the left of the reduction half-reaction listed below it in the table.
SIDE NOTE This is true when negative values for
So, starting with the first reaction
#Br_2#can oxidize #Ni#and #H_2#can reduce #Mn^(2+)#
The reduction half-reactions are
Bromine can oxidize nickel because its reduction half-reaction is lower in the table, i.e. it has a more positive
Hydrogen gas cannot reduce
#H^(+)#can oxidize #Fe#and #Ni#can reducce #Br_2#
As a result,
The last one will be obvious, since we've already established that bromine can oxidize nickel.
Nickel can reduce bromine because it has a more negative