1

### AIPMT 2011 Prelims

Standard electrode potential for Sn4+/Sn2+ couple is + 0.15 V and that for the Cr3+/Cr couple is $-$ 0.74 V. These two couples in their standard state are connected to make a cell. The cell potential will be
A
+ 1.19 V
B
+ 0.89 V
C
+ 0.18 V
D
+ 1.83 V

## Explanation

Sn4+/Sn2+ = 0.15 V

Cr3+/Cr = –0.74 V

cell = E°cathode – E°anode

= 0.15 – (– 0.74) = 0.15 + 0.74 = 0.89 V
2

### AIPMT 2011 Prelims

Standard electrode potential of three metals X, Y and Z are $-$1.2 V, + 0.5 V and $-$ 3.0 V respectively. The reducing power of these metals will be
A
Y > Z > X
B
Y > X > Z
C
Z > X > Y
D
X > Y > Z

## Explanation

As the electrode potential drops, reducing power increases.

So, Z (–3.0 V) > X (–1.2 V) > Y (+ 0.5 V)
3

### AIPMT 2010 Prelims

An increase in equivalent conductance of a strong electrolyte with dilution is mainly due to
A
increase in ionic mobility of ions
B
100% ionisation of electrolyte at normal dilution
C
increase in both i.e., number of ions and ionic mobility of ions
D
increase in number of ions.

## Explanation

Dilution of strong electrolytes increases ionisation, hence ionic mobility of ions increases which in turn increases equivalent conductance of the solution.
4

### AIPMT 2010 Prelims

For the reduction of silver ions with copper metal, the standard cell potential was found to be + 0.46 V at 25oC. The value of standard Gibb's energy, $\Delta$Go will be
(F = 96500 C mol$-$1)
A
$-$ 89.0 kJ
B
$-$ 89.0 J
C
$-$ 44.5 kJ
D
$-$ 98.0 kJ

## Explanation

The cell reaction

Cu + 2Ag+ $\to$ Cu2+ + 2Ag

We know, $\Delta$G° = – nFE°cell

= – 2 × 96500 × 0.46 = – 88780 J

= – 88.780 kJ = – 89 kJ