Reduction Potential Questions

Standard electrode potential of three metals $X,Y$ and $Z$ are $-1.2\text{V},+0.5\text{V}$ and $-3.0\text{V}$ respectively. The reducing power of these metals will be:

On the basis of the standard reduction potential values, the strongest oxidizing agent is (assuming common values for Iron complexes):

Four successive members of the first series of the transition metals are listed below. For which one of them the standard potential ($E_{M^{2+}/M}^{\circ }$) value has a positive sign?