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One Faraday of electricity is passed through molten Al₂O₃ , aqueous solution of CuSO₄ and molten NaCl taken in three different electrolytic cells connected in series. The mole ratio of Al, Cu and Na deposited at the respective cathode is

2: 3: 6
2: 3: 6
6 : 3 : 2
1 : 2: 3

102.

An alloy of Pb-Ag weighing 1.08 g was dissolved in dilute HNO₃ and the volume made to 100 mL. A silver electrode was dipped in the solution and the emf of the cell set up Pt(s), H₂ (g)| H⁺ (1M) || Ag⁺ (aq) | Ag(s) was 0.62V. If E^°_cell = 0. 80V. What is the percentage of Ag in the alloy? [At 25°C, RT / F = 0.06]

50
25
2.50
10

103.

The standard oxidation potentials of Zn, Cu, Ag and Ni electrodes are +0.76, 0.34, -0.80 and +0.25 V respectively. Which of the following reaction will provide maximum voltage?

Cu + 2Ag⁺(aq) → Cu²⁺(aq) + 2Ag
Zn + 2Ag⁺(aq) → Zn²⁺(aq) + 2Ag
H₂ + Ni²⁺(aq) → 2H⁺(aq) + Ni
Zn + Cu²⁺(aq) → Zn²⁺(aq) + Cu

104.

Both Co³⁺ and Pt⁴⁺ have a coordination number of six. Which of the following pairs of complexes will show approximately the same electrical conductance for their 0.001M aqueous solutions?

CoCl₃· 4NH₃ and PtCl₄. 4NH₃
CoCl₃ · 3NH₃ and PtCl₄ · 5NH₃
CoCl₃ · 6NH₃ and PtCl₄ · 5NH3
CoCl₃ . 6NH₃ and PtCl₄ . 3NH₃

105.
An alloy of Pb-Ag weighing 1.08g was dissolved in dilute HNO₃ and the volume made to 100 mL. A silver electrode was dipped in the solution and the emf of the cell set up Pt(s), H₂(g)|H⁺(1M) || Ag⁺(aq)|Ag(s) was 0.62V. If E°_cell= 0. 80V what is the percentage of Ag in the alloy? [At 25°C, RT IF= 0.06].

50

1

10

25

Pt(s), H₂(g)|H⁺(1M) || Ag⁺(aq)|Ag(s)

EMF of cell = 0.62V, E°_cell= 0. 80V

$H_{2} \to 2 H^{+} + 2 e^{-} (at anode) \frac{2 Ag + 2 e^{-} \to 2 Ag (at cathode)}{H_{2} + 2 {Ag}^{+} \to 2 Ag + 2 H^{+}} E_{cell} = E ° - \frac{2.303 RT}{2 F} \log \frac{[H]^{+}}{[{Ag}^{+}]^{2} [H_{2}]} E_{cell} = E ° - \frac{2.303 RT}{2 F} \log \frac{1}{[{Ag}^{+}]^{2}} 0.62 = 0.80 + \frac{2.303 \times 0.06}{2} \log \frac{1}{[{Ag}^{+}]^{2}} 0.62 = 0.80 + \frac{2 \times 2.303 \times 0.06}{2} \log [Ag]^{+} - 0.80 = 0.1382 \log [Ag]^{+} [Ag]^{+} = 0.05 M ∴ Moles of {Ag}^{+} in 100 mL = 0.05 \times \frac{100}{1000} wt . of {Ag}^{+} in 100 mL = 0.05 \times \frac{100}{1000} \times 108 % of Ag in 1.08 g alloy = \frac{0.05 \times 100 \times 108}{1000 \times 1.08} \times 100 = 50 %$

106.

The standard oxidation potentials of Zn, Cu, Ag and Ni electrodes are +0.76, 0.34, - 0.80 and +0.25 V respectively. Which of the following reaction will provide maximum voltage?

Cu + 2Ag⁺(aq) → Cu⁺² (aq) +2Ag
Zn + 2Ag⁺(aq) → Zn²⁺(aq) + 2Ag
H₂ + Ni²⁺ (aq) → 2H⁺(aq) + Ni
Zn + Cu²⁺(aq) → Zn²⁺(aq) + Cu

107.

The standard electrode potentials of Ag⁺/Ag is +0.80V and Cu⁺/Cu is +0.34 V. These electrodes are connected through a salt bridge and if:

copper electrode acts as a cathode then E° cell is +0.46 V
silver electrode acts as anode then E^° cell is -0.34 V
copper electrode acts as anode then E° cell is +0.46 V
silver electrode acts as a cathode then E° cell is -0.34 V

108.

If three Faradays of electricity is passed through the solutions of AgNO₃, CusO₄ and AuCl₃, the molar ratio of the cations deposited at the cathodes will be :

1 : 1 : 1
1 : 2 : 3
3 : 2 : 1
6 : 3 : 2

109.

E $_{Cu}^{°}$ - 0.34 V; E $_{Zn}^{°}$ = 0.76 V. A Daniel cell contains 0.1 M ZnSO₄ solution and 0.01M CuSO₄ solution at its electrodes. EMF of the cell is: