$X$, $Y$ and $Z$ are three different halogens. The table records the outcomes of nine experiments in which aqueous solutions of $X_2$, $Y_2$ and $Z_2$ were each added separately to separate aqueous solutions containing $X^-,$ $Y^-$ and $Z^-$ ions. Which row in the table below lists the ions $X^-$, $Y^-$ and $Z^-$ in order of decreasing reducing strength?
Chemistry 9701 · AS & A Level · Electrochemistry