511.

For a fuel cell, which statementis correct?

• Hydrogen is oxidised to H₂O at cathode

• Oxygen is reduced to OH^- at anode

• Hydrogen is oxidised to H₂O at anode

• Hydrogen is oxidised to H⁺ at anode

An example for a strong electrolyte is

• urea

• ammonium hydroxide

• sugar

• sodium acetate

2 × 10^-5C charge on Zn²⁺  ions corresponds to

• 2 × 10^-5 mol of Zn²⁺ ions

• 6.22  × 10⁷ Zn²⁺ ions

• 0.64 mg of Zn²⁺ ions

• 1 × 10^-10 mol Zn²⁺ ions.

What is the.standard potential of the Tl³⁺/ Tl electrode?

Tl³⁺ +2e^- → Tl⁺, E°= 1.26V

Tl⁺ +e^- → Tl, E°=-0.336V

• 0.924V

• -0.924 V

• 0.728 V

• -0.728V

One litre of 1 M CuSO₄ solution is electrolysed. After passing 2F charge, the molarity of CuSO₄ solution will be

• M/2

• Zero

• M/4

• M

Same amount of electric current is passed through solutions of AgNO₃ and HCl. If 1.08 g of silver is obtained in the first case, the amount of hydrogen liberated at STP in the second case is

• 224 cm³

• 1.008 gm

• 112 cm³

• 22400 cm³

The standard reduction potentials of Zn and Ag in water at 298 K are, Zn²⁺ + 2e^- $\rightleftharpoons$ Zn; E° = -0.76 V and Ag⁺ + e^- $\rightleftharpoons$ Ag; E° = +0.80 V? Which of the following reactions take place?

• Zn²⁺ (aq) + 2Ag (s) → 2Ag⁺ (aq) + Zn (s)

• Zn (s) + 2Ag⁺ (aq) → Zn²⁺ (aq) + 2Ag (s)

• Zn²⁺ (aq) + Ag⁺ (aq) → Zn (s) + Ag (s)

• Zn (s) + Ag (s) → Zn²⁺ (aq) + Ag⁺ (aq)

In a galvanic cell, the electrons flow from

• anode to cathode through the solution

• cathode to anode through the solution

• anode to cathode through the external circuit

• cathode to anode through the external circuit

Aluminium displaces hydrogen from dilute HCl whereas silver does not. The e.m.f. of a cell prepared by combining Al / Al³⁺ 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

• -3.26 V

• 3.26 V

• -1.66 V

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