Question

Write the equation for the reaction, if any, that occurs when each of the following experiments is performed under standard conditions.
a) crystals of iodine are added to an aqueous solution of potassium bromide.
b) liquid bromine is added to an aqueous solution of sodium chloride.
c) a chromium wire is dipped into a solution of nickle (II) chloride.

From the information given, how would I determine whether or not the reactions occur?

For all of them you can use a table of reduction potentials. Do you have that? If not, the Activity series will answer the Cr, Ni question. For the halogens, the reactivity goes from F2>Cl2>Br2>I2, meaning F2 will displace any ion (Cl^-, Br^-, I^-) below it. But not the other way around.

I have a table of reduction potentials, but I'm not really sure how to use it to solve this problem. A lot of the substances listed in the problems (for example, KBr) don't exist on the table. Would this mean that the reaction doesn't exist?