The cell reaction for a certain alkaline dry cell is Mgs 2M

The cell reaction for a certain alkaline dry cell is

Mg(s) + 2MnO2(s) + H2O(l)Mg(OH)2(s) + Mn2O3(s)Mg(s) + 2MnO2(s) + H2O(l)Mg(OH)2(s) + Mn2O3(s)
Which of the following statements concerning this cell is/are incorrect?

.1.MnO2(s) is oxidized to Mn2O3(s) during cell discharge.

2. Water is consumed during the discharge of this cell.

3.Mg(OH)2(s) forms at the anode during discharge of this cell.

Select one:

a. 1 only

b. 2 only

c. 3 only

d. 2 and 3

e. 1, 2 and 3

Solution

Oxidation state of Mn in MnO2 is +4 and in Mn2O3 it is +3.(To get oxidatio state of Mn take oxidation state of each atom of O to be -2. So oxidation state of Mn =number of atoms of O*(2)/number of atoms of Mn)

This means oxidation state of Mn is reduced from +4 to +3.Hence Mn is reduced and not oxidized where as Mg is oxidized.So statement 1 is wrong.

During discharge forward reaction occurs.In forward reaction water is consumed, so statement 2 is correct.

At anode oxidation process occurs.Mg to oxidized.Thus statement 3 is correct.

Hence is d. 2 and 3.