451.

Na is used in reduction of Zn salt because

• E°_{Zn (oxi)} > E°_{Na (oxi)}

• E°_{Zn (red)} > E°_{Na (red)}

• E°_{Zn (oxi)} < E°_{Na (oxi)}

• both (a) and (b)

Reduction potentials of A, B, C and D are 0.8 V, 0.79 V, 0.34 V and -2.37 V respectively. Which element displaces all the other three elements?

• B

• A

• D

• C

During the electrolytic reduction of alumina, the reaction at cathode is

• 2H₂O → O₂ + 4H⁺ + 4e^-

• 3F^- → 3F + 3e^-

• Al³⁺ + 3e^- → Al

• 2H⁺ + 2e^- → H₂

One ampere of current is passed for 9650 seconds through molten AlCl₃. What is the weight in grams of Al deposited at cathode? (atomic weight of Al = 27)

• 0.9

• 9.0

• 0.09

• 90.0

Molten CuCl₂ is electrolysed using platinum electrodes. The reaction occurring at anode is

• 2Cl^- → Cl₂ (g) + 2e^-

• Cl₂(g) + 2e^- → 2Cl

• Cu²⁺ + 2e^- → Cu (s)

• Cu(s) → Cu²⁺ + 2e^-

During the electrolysis of cryolite, aluminium and fluorine are formed in ...... molar ratio :

• 1:2

• 2:3

• 1:1

• 1:3

What is the reduction electrode potential (in volts) of copper electrode when [Cu²⁺] = 0.01 M is in a solution at 25°C?

(E° of Cu²⁺/ Cu electrode is + 0.34 V)

• 0.3991

• 0.2809

• 0.3105

• 0.3695

The product obtained at anode when 50% H₂SO₄ aqueous solution is electrolysed using platinum electrodes is :

• H₂SO₃

• H₂S₂O₈

• O₂

• H₂

0.066 g of metal was deposited when a current of 2 ampere is passed through a metal ion solution for 100 seconds. What is the electrochemical equivalent (in gram coulomb^-1) of the metal ?

• 3.3 × 10^-6

• 3.3 × 10^-4

• 0.033

• 3.3

When X amperes of current is passed through molten AlCl₃ for 96.5 s, 0.09g of aluminium is deposited. What is the value of X?

• 10 ampere

• 20 ampere

• 30 ampere

• 40 ampere