Chemistry 9701 · AS & A Level · Electrochemistry

Electrochemistry — practice question

U, V and W are three different halogens. The table summarises nine experiments in which aqueous $\text{U}_2$, $\text{V}_2$ and $\text{W}_2$ were each added separately to aqueous solutions containing $\text{U}^-$, $\text{V}^-$ and $\text{W}^-$ ions. (Results summary) $\text{U}_2(aq)$ does not react with $\text{U}^-(aq)$, $\text{V}^-(aq)$ or $\text{W}^-(aq)$. $\text{V}_2(aq)$ produces $\text{U}_2$ with $\text{U}^-(aq)$, does not react with $\text{V}^-(aq)$, and produces $\text{W}_2$ with $\text{W}^-(aq)$. $\text{W}_2(aq)$ produces $\text{U}_2$ with $\text{U}^-(aq)$ and does not react with $\text{V}^-(aq)$ or $\text{W}^-(aq)$. Which row gives the ions $\text{U}^-$, $\text{V}^-$ and $\text{W}^-$ in descending order of reducing strength?

  • Astrongest $\text{U}^-$ $\rightarrow$ weakest $\text{V}^-$ $\rightarrow$ $\text{W}^-$
  • Bstrongest $\text{U}^-$ $\rightarrow$ weakest $\text{W}^-$ $\rightarrow$ $\text{V}^-$
  • Cstrongest $\text{V}^-$ $\rightarrow$ weakest $\text{W}^-$ $\rightarrow$ $\text{U}^-$
  • Dstrongest $\text{W}^-$ $\rightarrow$ weakest $\text{U}^-$ $\rightarrow$ $\text{V}^-$

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