921) A reducing agent is one that causes something to be reduce, while itself is oxidized. Therefore, I would look for the negative values in the standard potential table. I would choose the highest value, so does that mean I choose the least negative value, i.e. closer to 0.

972) I thought it would be all of the above. Why do they only choose only Q<K?

990) Do you have to use the redox balancing method. If you do, I could not get the correct answer. Could someone show me the method of arriving at that particular answer?