22298.A button cell used in watches functions as follows:
Zn(s) + Ag2O(s) + H2O(l) → 2Ag(s) + Zn2+(aq) + 2OH– (aq)
If half cell potentials are
Zn2+ (aq) + 2e– → Zn(s); E° = –0.76 V
Ag2O(s) + H2O(l) + 2e– → 2Ag(s)+ 2OH–(aq), E° = 0.34 V
The cell potential will be
1.10 V
0.42 V
0.84 V
1.34 V
22299.Aluminium displaces hydrogen from dilute HCl whereas silver does not. The E.M.F. of a cell prepared by combining Al/Al+3 and Ag/Ag+ is 2.46 V. The reduction potential of silver electrode is + 0.80 V. The reduction potential of aluminium electrode is:
+1.66 V
–1.66 V
3.26 V
–3.26 V
22300.The reduction potential values of X, Y and Z are –3.05 V, –0.44 V and –0.83 V respectively. Which of the following order is correct with respect to their reducing property?
X > Y > Z
X > Z > Y
Y > Z > X
Z > Y > X
22301.For a cell reaction involving two electrons change, the standard e.m.f. of the cell is found to be 0.295 V at 25°C. The equilibrium constant of the reaction at 25°C is
2.95 × 102
10
1 × 1010
1 × 10–10
22302.When KMnO4 acts as an oxidizing agent and ultimately forms MnO2–
4, MnO2, Mn2O3 and Mn2+, then the number of electrons transferred in each case is
4, MnO2, Mn2O3 and Mn2+, then the number of electrons transferred in each case is
1, 3, 4, 5
1, 5, 3, 7
4, 3, 1, 5
3, 5, 7, 1
22303.What is the time (in sec) required for deposition all the silver present in 125mL of 1 MAgNO3 solution by passing a current of 241.25 amperes? (1F = 96500 coulombs)
10
50
1000
100
22304.On the basis of the following E° values, the strongest oxidizing agent is:
[Fe(CN)6]4– → [Fe(CN)6]3– + e–1; E° = –0.35 V
Fe2+ → Fe3+ + e–1; E° = –0.77 V
Fe2+
Fe3+
[Fe(CN)6]3–
[Fe(CN)6]4–
22305.A hydrogen gas electrode is made by dipping platinum wire in a solution of HCl of pH = 10 and by passing hydrogen gas around the platinum wire at one atm pressure. The oxidation potential of electrode would be
0.059 V
0.59 V
0.118 V
1.18 V
22306.Accumulation of lactic acid (HC3H5O3), a monobasic acid in tissues leads to pain and a feeling of fatigue. In a 0.10 M aqueous solution, lactic acid is 3.7% dissociates. The value of dissociation constant, Ka, for this acid will be:
2.8 × 10–4
1.4 × 10–5
1.4 × 10–4
3.7 × 10–4
22307.Faraday’s constant is defined as
charge carried by 1 electron
charge carried by one mole of electrons
charge required to deposit one mole of a substance
charge carried by two moles of electrons
22308.A solution of nickel sulphate in which nickel rod is dipped is diluted 10 times. The reduction potential of Ni at 298 K
decreases by 60 mV
decreases by 30 mV
decreases by 30 V
increases by 30 mV
22309.Al2O3 is reduced by electrolysis at low potentials and high currents. If 4.0 × 104 amperes of current is passed through molten Al2O3 for 6 hours, what mass of aluminium is produced? (Assume 100% current efficiency, atomic mass of Al = 27 g/mol)
1.3 × 104 g
2.4 × 105 g
8.1 × 104 g
9.0 × 103 g
22310.Aluminium oxide may be electrolyzed at 1000°C to furnish aluminium metal (At. Mass = 27 amu; 1 Faraday = 96,500 Coulombs). The cathode reaction is
Al3+ + 3e– → Al.
Al3+ + 3e– → Al.
1.83 × 107 C of electricity
5.49 × 107 C of electricity
5.49 × 101 C of electricity
5.49 × 104 C of electricity
22311.A certain current liberates 0.504 g of hydrogen in 2 hours. How many grams of oxygen can be liberated by the same current in same time?
2.0 g
0.4 g
4.0 g
8.0 g
22312.The molar conductivities Λo
NaOAc and Λo
HCl at infinite dilution in water at 25°C are 91.0 and 426.2 S cm2/mol respectively. To calculate Λo
HoAc, the additional value required is
NaOAc and Λo
HCl at infinite dilution in water at 25°C are 91.0 and 426.2 S cm2/mol respectively. To calculate Λo
HoAc, the additional value required is
Λo
H2O
H2O
Λo
KCl
KCl
Λo
NaOH
NaOH
Λo
NaCl
NaCl
22313.Aluminium displaces hydrogen from acids, but copper does not. A galvanic cell prepared by combining Cu/Cu2+ and Al/Al3+ has an emf of 2.0 V at 298 K. If the potential of copper electrode is +0.34 V, that of aluminium electrode is
–2.3 V
+2.34 V
–1.66 V
1.66 V
22314.The specific conductance of 0.1 M NaCl solution is 1.06 × 10–2 ohm–1 cm–1. Its molar conductance in ohm–1 cm2 mol–1 is
1.06 × 102
1.06 × 103
1.06 × 104
53 × 102
22315.Among the following cells
Leclanche cell (I)
Nickel–cadmium cell (II)
Lead storage battery (III)
Mercury cell (IV)
Leclanche cell (I)
Nickel–cadmium cell (II)
Lead storage battery (III)
Mercury cell (IV)
Primary cells are
I and II
I and III
II and III
I and IV
22316.The hydrogen electrode is dipped in a solution of pH 3 at 25°C. The potential would be (the value of 2.303 RT/F is 0.059 V)
0.177 V
0.087 V
0.059 V
–0.177 V
22317.When same quantity of electricity is passed for half an hour, the amount of Cu and Cr deposited are respectively 0.375 g and 0.30 g. Ratio of electrochemical equivalent of Cu and Cr is
0.8
1.25
2.5
1.62