1
MCQ (Single Correct Answer)

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
MCQ (Single Correct Answer)

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
MCQ (Single Correct Answer)

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
MCQ (Single Correct Answer)

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

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