oxidation half reaction question?

Question

Given the following net ionic equation:

2 Al_(s)  + 6 H⁺_(aq)  →  2 Al³⁺_(aq)   +  3 H_2(g)

The reaction that represent the oxidation half-reaction is:

Question 6 options:

a.	Al(s) →  Al3+(aq) + 3 e−
b.	2 H+(aq) + 2 e−→ H2(g)
c.	Al3+(aq) + 3 e−  →Al(s)
d.	H2(g) → 2H+(aq) + 2 e−

Answer 1

(a) Al(s) ===> Al³⁺ + 3e^-

Oxidation is an increase in oxidation number, or a loss of electrons. This is the case when Al(s) has an oxidation number of zero, and then the Al³⁺ cation has an oxidation number of 3+.