Electrochemistry

For a salt XY, which is a strong electrolyte, the plot of m versus c has a slope of -90.0 S cm2 mol-3/2 L1/2 at 298 K. At 0.01 M concentration of XY, the value of m is 145.0 S cm2 mol-1. The limiting molar conductivity of Y- ion ( Y-0, in S cm2 mol-1) at 298 K will be (Given : X+0 = 74.0 S cm2 mol-1)

1. 76.0
2. 80.0
3. 100.0
4. 90.0

If the molar conductivity ( m) of a 0.050 mol L-1 solution of a monobasic weak acid is 90 S cm2 mol-1, its extent (degree) of dissociation will be [Assume + = 349.6 S cm2 mol-1 and - = 50.4 S cm2 mol-1.]

1. 0.225
2. 0.215
3. 0.115
4. 0.125

Match List I with List II. Choose the correct answer from the options given below :

1. A-II, B-IV, C-I, D-III
2. A-III, B-IV, C-I, D-II
3. A-II, B-III, C-I, D-IV
4. A-III, B-IV, C-II, D-I

Mass in grams of copper deposited by passing 9.6487 A current through a voltameter containing copper sulphate solution for 100 seconds is (Given : Molar mass of Cu: 63 g mol-1, 1 F = 96487 C)

1. 3.15 g
2. 0.315 g
3. 31.5 g
4. 0.0315 g

From the following select the one which is not an example of corrosion.

1. Rusting of iron object
2. Production of hydrogen by electrolysis of water
3. Tarnishing of silver
4. Development of green coating on copper and bronze ornaments

The standard cell potential of the following cell Zn | Zn2+(aq) || Fe2+(aq) | Fe is 0.32 V. Calculate the standard Gibbs energy change for the reaction: Zn(s) + Fe2+(aq) Zn2+(aq) + Fe(s) (Given : 1 F = 96487 C)

1. -61.75 kJ mol-1
2. +5.006 kJ mol-1
3. -5.006 kJ mol-1
4. +61.75 kJ mol-1

The conductivity of centimolar solution of KCl at 25 is 0.0210 ohm-1 cm-1 and the resistance of the cell containing the solution at 25 is 60 ohm. The value of cell constant is -

1. 3.28 cm-1
2. 1.26 cm-1
3. 3.34 cm-1
4. 1.34 cm-1

Given below are two statements: one is labelled as Assertion A and the other is labelled as Reason R: In the light of the above statements, choose the correct answer from the options given below:

1. Both A and R are true but R is NOT the correct explanation of A.
2. A is true but R is false.
3. A is false but R is true.
4. Both A and R are true and R is the correct explanation of A.

At 298 K, the standard electrode potentials of Cu2+/Cu, Zn2+/Zn, Fe2+/Fe and Ag+/Ag are 0.34 V, -0.76 V, -0.44 V and 0.80 V, respectively. On the basis of standard electrode potential, predict which of the following reaction cannot occur?

1. CuSO4(aq) + Zn(s) ZnSO4(aq) + Cu(s)
2. CuSO4(aq) + Fe(s) FeSO4(aq) + Cu(s)
3. FeSO4(aq) + Zn(s) ZnSO4(aq) + Fe(s)
4. 2CuSO4(aq) + 2Ag(s) 2Cu(s) + Ag2SO4(aq)

Given below are half cell reactions: MnO4- + 8H+ + 5e- Mn2+ + 4H2O, E Mn2+/MnO4- = -1.510 V 12O2 + 2H+ + 2e- H2O E O2/H2O = +1.223 V Will the permanganate ion, MnO4- liberate O2 from water in the presence of an acid?

1. Yes, because E cell = +0.287 V
2. No, because E cell = -0.287 V
3. Yes, because E cell = +2.733 V
4. No, because E cell = -2.733 V