EΘ values of some redox couples are given below. On the basis of these values choose the correct option.

EΘ values: Br2/Br-=+1.90Ag+/Ag(s)=+0.80Cu2+/Cu(s)=+0.34; I2(s)/I-=+0.54

1. Cu will reduce Br-

2. Cu will reduce Ag

3. Cu will reduce I-

4. Cu will reduce Br2

Hint: High reduction potential substance is a good oxidising agent
 
The given values of E° are as follows:
 
Br2/Br-=+1.90VAg/Ag+=-0.80VCu2+/Cu(s)=+0.34VI-/I2(s)=-0.54 VBr-/Br2=-1.90V
The E° values show that copper will reduce Br2, if the E° of the following redox reaction is positive.
 
2Cu+Br2CuBr2CuCu2++2e-; E°=-0.34VBr2+2e-2Br-; E=+1.09VCu+Br2CuBr2; E°=+0.75 V
Since, E° of this reaction is positive, therefore, Cu can reduce Br2.
 
While other reaction will give negative value.