Identify the half reaction as oxidation or reduction.

sn > sn2+ + 2e¯
cl2 + 2e¯ > 2cl¯

OILRIG:
Oxidation is loss (of electrons)
Reduction is gain (of electrons)
so...
The first one is an oxidation half-equation as the Sn loses electrons;
The second one is a reduction half-equation as the Cl₂ gains electrons

C) electrons encircling a nucleus with neutrons and protons

Ok so co(g) is not pronoused that. the only clue is that youpronouse it the oppisote way.