in the reaction:Ni+SN4+-->Ni2+ (+)Sn2+ which species has been reduced?

1.Ni
2.Sn4+
3.Ni2+
4.Sn2+

i know its def Sn but im not sure which one.

In the given reaction, Ni+SN4+ --> Ni2+ (+) Sn2+, the species that has been reduced is the Sn4+ ion.

To determine which species has been reduced in the given reaction, you need to identify the change in the oxidation state (or oxidation number) of each species involved.

In the reaction: Ni + Sn4+ → Ni2+ + Sn2+

The oxidation state of nickel (Ni) changes from 0 to +2. This indicates that nickel has been oxidized and lost electrons.

On the other hand, the oxidation state of tin (Sn) changes from +4 to +2. This implies that tin has been reduced and gained electrons.

Therefore, in this reaction, the species Sn4+ has been reduced to Sn2+. So, the answer is:

4. Sn2+

Remember Leo the Lion goes Grr. The key word is Leo; i.e., loss electrons oxidation. So reduction is the gain of electrons. If you know it's Sn, then does Sn gain electrons in going from Sn+4 to Sn+2 or from Sn+2 to Sn+4.