MCQ
A cell constructed by coupling a standard copper electrode and a standard magnesium electrode has emf of $2.7$ volts. If the standard reduction potential of copper electrode is $+ 0.34 $ volt that of magnesium electrode is .............. $\mathrm{V}$
  • A
    $+ 3.04$  
  • B
    $-3.04 $ 
  • C
    $+ 2.36 $ 
  • $-2.36$  

Answer

Correct option: D.
$-2.36$  
d
(d)$Mg $ lies above $Cu$  in electrochemical series and hence $Cu $ electrode acts as cathode
$E_{cell}^o = E_{C{u^{ + 2 }}/Cu}^o - E_{M{g^{ + 2 }}/Mg}^o$$2.70\,\,V = 0.34 - E_{M{g^{ + 2 }}/Mg}^o$; $E_{M{g^{ + 2 }}/Mg}^o = - 2.36\,\,V$.

Need a full question paper?

Generate a complete, print-ready paper with questions like this in minutes — across 16+ boards, with answer keys.

Start Generating Free