Question # 1

The standard e.m.f. of a galvanic cell involving cell reaction with n = 2 is found to be 0.2965 V at 25°C. The equilibrium constant of the reaction would be

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1.0 x 10¹⁰

2.0 x 10¹¹

4.0 x 10¹²

1.0 x 10²

The reaction is galvanic cell is

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Spontaneous

Non-spontaneous

Acid-base

None of these

Alkaline battery has a voltage of

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4.5 V

3.5 V

2.5 V

1.5 V

The reduction potential to copper electrode is +0.34 V and that of Zn electrode is -0.76 V. when these two are coupled the e.m.f. of the cell is

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-0.42 V

+0.42

-1.10 V

+1.10 V

Best way to prevent rusting of iron is by

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Making iron cathode

Putting it in saline water

Both of these

None of these

Zn does not displace Mg from MgSO₄solution because

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Zn is more electropositive than Mg

Zn is below Mg in electropositive series

Zn is above Mg in electrochemical series

Zn is trivalent Mg is divalent

In electrolysis of NaCl when Pt electrode is taken then H₂is liberated at cathode while with Hg cathode it forms sodium amalgam

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Hg is more inert than Pt

More voltage is required to deduce H⁺at Hg than Pt

Na is dissolved in Hg while it does not dissolve in Pt

Conc. of H⁺ions is larger when Pt electrode is taken

The function of salt bridge is :

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To increase movement onions.

To increase the emf of cell.

To decrease the temperate

To maintain electrical neutrality

If the standard electrode potential of CU²⁺/Cu electrode is 0.34 V, what is the electrode potential of 0.01 M concentration of Cu²⁺? (T=298)

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0.399 V

0.281 V

0.222 V

0.176 V

Which one of the following reaction takes place spontaneously

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Which of the following (1 M) conducts more electricity?

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Sulphuric acid

Boric acid

Nitric acid

Phosphorus acid

96500 C of electricity liberates from CuSO₄solution

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63.5 g of Cu

31.75 g of Cu

96500 g of Cu

100 g of Cu

An electric current is passed through silver voltameter connected to a water voltmeter. The cathode of the silver voltameter is 0.108 g more at the end of the electrolysis. The volume of oxygen evolved at STP is

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56 cm³

550 cm³

5.6 cm³

11.2 cm³

Coinage metals like Au, Pt, Ag and Cu are the least reactive metals and don't liberate H₂gas when treated with acids because

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These have very high positive values of reduction potentials

These have very high negative values of reduction potentials

Their ionization potentials are lowest

Their reduction potentials are close to SHE

An electrolyte

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Forms complex ions solution

Gives ions only when electricity is passed

Possesses ions even in solid state

Gives ions only when dissolved in water

Matals usually conduct electricity because

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There are mobile electrons in the metallic structure

Metals are decomposed by current

Metals have high resistance

In metals the ions are free to move

A solution of sodium sulphate was electrolysed using some insert electrodes. The products at the electrodes are

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O₂, H₂

O₂, Na

O₂, SO₂

O₂, S₂O₈²

When aluminium electrode is coupled with copper electrode in a galvanic cell :

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Reduction takes place at aluminium electrode.

Oxidation takes place at copper electrode.

Reduction takes place at copper electrode.

Both (a) and (c)

During electrolysis of KNO₃, H₂is evolved

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Anode

Cathode

Both a and b

None

The oxidation number of free element is always taken to be

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0

1

2

-1

The equivalent conductivity of 0.1 M week acid is 100 times less than at infinite dilution. The degree of dissociation is

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100

10

0.01

0.001

Which of the following cannot conduct electricity :

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NaCl fused.

NaCl(aq)

NaCl(Solid)

Both (b) and (c)

A dry alkaline cell has porous Zn anode and MnO₂as cathode the electrolyte used is

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Ca(OH)₂

NaOH

KOH

NH₄OH

Metals like Fe, Mg, Al, Cr, Zn have more negative reduction potentials that is whey

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These don't react with steam

These react very slowly with steam to liberate H₂gas

These react rapidly with steam to produce the metallic oxides and liberate H₂gas

These react with cold water violently

During electrolysis, the reaction that takes place at cathode is :

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Reduction

Both (a) and (c)

Oxidation

No reaction occurs

Strong oxidizing agents have

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Greater positive value of standard reduction potential

Lesser positive value of standard

Greater negative value of standard

None of these

The oxidation number of chromium in K₂Cr₂O₇is

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14

12

6

None of these

Electrolysis is used for :

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Manufacture of caustic soda

Refining of copper

Electroplating

All of above

When electrically is passed through molten Al₂O₃+ Na₃AlF₆and 13.5 gms of Al are deposited, the number of farady must be

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0.5

1.0

1.5

2.0

In the reaction K₂Cr₂O₇+ HCl + CrCl₃+ Cl₂+ H₂O the element which is reduced is

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K

Cl

Cr

H

When during electrolysis of a solution of AgNO₃, 9650 coulombs of charge pass through the electroplating bath, the mass of silver deposited on the cathode will be

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1.08 g

10.8 g

21.6 g

108 g

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