# Electrochemistry Test 3

Total Questions:50 Total Time: 75 Min

Remaining:

## Questions 1 of 50

Question:When lead storage battery is charged

Sulphuric acid is regenerated

The amount of sulphuric acid decreases

## Questions 2 of 50

Question:The electrolytic decomposition of dilute sulphonic acid with platinum electrode in cathodic reaction is

Oxidation

Reduction

Oxidation and reduction both

Neutralisation

## Questions 3 of 50

Question:The specific conductance of a solution is 0.2 $$oh{m^{ - 1}}c{m^{ - 1}}$$and conductivity is 0.04 $$oh{m^{ - 1}}$$. The cell constant would be

1 $$c{m^{ - 1}}$$

0 $$c{m^{ - 1}}$$

5 $$c{m^{ - 1}}$$

0.2 $$c{m^{ - 1}}$$

## Questions 4 of 50

Question:If the conductance and specific conductance of a solution is one then its cell constant would be

1

Zero

0.5

4

## Questions 5 of 50

Question:In electroplating, the article to be electroplated serves as

Cathode

Electrolyte

Anode

Conductor

## Questions 6 of 50

Question:The position of some metals in the electrochemical series in decreasing electropositive character is given as $$Mg > Al > Zn > Cu > Ag.$$ What will happen, if a copper spoon is used to stir a solution of aluminium nitrate

The spoon will get coated with $$Al$$

An alloy of $$Cu$$ and $$Al$$ is formed

The solution becomes blue

There is no reaction

## Questions 7 of 50

Question:The chemical reaction, $$2AgCl(s) + {H_2}(g)\; \to$$ $$2HCl(aq) + 2Ag(s)$$ taking place in a galvanic cell is represented by the notation

$$Pt|{H_2}(g),1{\rm{bar|1}}M\;KCl(aq)|AgCl(s)|Ag(s)$$

$$Pt(s)|{H_2}(g),\;1{\rm{bar|}}\;1M\;HCl(aq)||1M\;A{g^ + }(aq)|Ag(s)$$

$$Pt(s)|{H_2}(g),\;1{\rm{bar|}}\;1M\;HCl(aq)|AgCl(s)|Ag(s)$$

$$Pt(s)|{H_2}(g),\;1{\rm{bar|}}\;1M\;HCl(aq)|Ag(s)|AgCl(s)$$

## Questions 8 of 50

Question:If the $$Z{n^{2 + }}/Zn$$ electrode is diluted to 100 times then the change in e.m.f.

Increase of $$59\,mV$$

Decrease of $$59\,mV$$

Increase of $$29.5\,mV$$

Decrease of $$29.5\,mV$$

## Questions 9 of 50

Question:Which of the following shows electrical conduction

Potassium

Graphite

Diamond

Sodium

## Questions 10 of 50

Question:The unit of equivalent conductivity is

ohm cm

$$oh{m^{ - 1}}c{m^2}\,{(gm\,\;equivalent)^{ - 1}}$$

ohm $$c{m^2}\,(gm\,\,equivalent)$$

$$S\,c{m^{ - 2}}$$

## Questions 11 of 50

Question:Corrosion is basically a

Altered reaction in presence of $${H_2}O$$

Electrochemical phenomenon

Interaction

Union between light metal and heavy metal

## Questions 12 of 50

Question:Rusting of iron is catalysed by which of the following

$$Fe$$

$${O_2}$$

$$Zn$$

$${H^ + }$$

## Questions 13 of 50

Question:When a copper wire is placed in a solution of $$AgN{O_3}$$, the solution acquires blue colour. This is due to the formation of

$$C{u^{2 + }}$$ ions

$$C{u^ + }$$ ions

Soluble complex of copper with $$AgN{O_3}$$

$$C{u^ - }$$ ion by the reduction of $$Cu$$

## Questions 14 of 50

Question:Consider the reaction $$M_{(aq)}^{n + } + n{e^ - } \to {M_{(s)}}$$. The standard reduction potential values of the elements $${M_1},\,{M_2}$$ and $${M_3}$$ are $$- 0.34V,\, - \,3.05\,V$$ and $$- 1.66\,V$$ respectively. The order of their reducing power will be

$${M_1} > {M_2} > {M_3}$$

$${M_3} > {M_2} > {M_1}$$

$${M_1} > {M_3} > {M_2}$$

$${M_2} > {M_3} > {M_1}$$

## Questions 15 of 50

Question:The standard electrode potential for the two electrode $${A^ + }/A$$ and $${B^ + }/B$$ are respectively 0.5 $$V$$ and 0.75 $$V$$. The $$emf$$ of the given cell $$A\,\,|\,\,{A^ + }(a = 1)\,\,||\,\,{B^ + }(a = 1)\,\,|\,\,B$$ will be

1.25 $$V$$

-1.25 $$V$$

-0.25 $$V$$

0.25 $$V$$

## Questions 16 of 50

Question:The standard reduction potential for $$L{i^ + }/Li\,;\,\,Z{n^{2 + }}/Zn\,;$$ $${H^ + }/{H_2}$$ and $$A{g^ + }/Ag$$ is $$- 3.05,\,\, - 0.762,\,\,0.00$$ and $$+ 0.80\,\,V.$$ Which of the following has highest reducing capacity

$$Ag$$

$${H_2}$$

$$Zn$$

$$Li$$

## Questions 17 of 50

Question:A standard hydrogen electrode has zero electrode potential because

Hydrogen is easiest to oxidize

The electrode potential is assumed to be zero

Hydrogen atom has only one electron

Hydrogen is the lightest element

In the electrochemical cell

## Questions 18 of 50

Question:$${H_2}(g)\,1\,atm\,|{H^ + }(1M)||C{u^{2 + }}(1M)\,|Cu(s)$$. Which one of the following statements is true

$${H_2}$$ is cathode; $$Cu$$ is anode

Oxidation occurs at $$Cu$$ electrode

Reduction occurs at $${H_2}$$ electrode

$${H_2}$$ is anode; $$Cu$$ is cathode

## Questions 19 of 50

Question:$${E^o}$$ for the cell $$Zn|Z{n^{2 + }}(aq)||C{u^{2 + }}(aq)|Cu$$ is $$1.10\,V$$ at $${25^o}C$$, the equilibrium constant for the reaction $$Zn + C{u^{2 + }}(aq)$$?$$Cu + Z{n^{2 + }}(aq)$$ is of the order of

$${10^{ - 28}}$$

$${10^{ - 37}}$$

$${10^{ + 18}}$$

$${10^{ + 17}}$$

## Questions 20 of 50

Question:Standard reduction potentials at $${25^o}C$$ of $$L{i^ + }|Li,\,B{a^{2 + }}|\,Ba,\,N{a^ + }|\,Na$$ and $$M{g^{2 + }}|Mg$$ are $$- 3.05,\, - 2.90,\, - 2.71$$ and $$- 2.37$$ volt respectively. Which one of the following is the strongest oxidising agent

$$N{a^ + }$$

$$L{i^ + }$$

$$B{a^{2 + }}$$

$$M{g^{2 + }}$$

## Questions 21 of 50

Question:For the electrochemical cell, $$M|{M^ + }||{X^ - }|X,$$$${E^o}({M^ + }/M)$$ = 0.44 V and $${E^o}(X/{X^ - })$$= 0.33 V. From this data one can deduce that

$$M\, + \,X\, \to {M^ + } + {X^ - }$$ is the spontaneous reaction

$${M^ + } + {X^ - } \to M + X$$ is the spontaneous reaction

$${E_{cell}}$$= 0.77 V

$${E_{cell}}$$= – 0.77 V

## Questions 22 of 50

Question:The standard potential at $${25^o}C$$ for the following half reactions are given against them $$Z{n^{2 + }} + 2e \to Zn,{E^o} = - 0.762V$$$$M{g^{2 + }} + 2e \to Mg,{E^o} = - 2.37V$$When zinc dust is added to the solution of $$MgC{l_2}$$

$$ZnC{l_2}$$is formed

Zinc dissolves in the solution

No reaction takes place

$$Mg$$is precipitated

## Questions 23 of 50

Question:Zinc displaces copper from the solution of its salt because

Atomic number of zinc is more than that of copper

Zinc salt is more soluble in water than the copper salt

Gibbs free energy of zinc is less than that of copper

Zinc is placed higher than copper in electro-chemical series

## Questions 24 of 50

Question:An electrochemical cell is set up as follows $$Pt({H_2},\,1\,atm)/0.1\,M\,HCl$$ || 0.1 M acetic acid /( $${H_2},\,1\,atm$$) Pt E.M.F. of this cell will not be zero because

The $$pH$$ of 0.1 M HCl and 0.1 M acetic acid is not the same

Acids used in two compartments are different

E.M.F. of a cell depends on the molarities of acids used

The temperature is constant

## Questions 25 of 50

Question:For the electrochemical cell, $$M|{M^ + }||{X^ - }|X,$$ $$E^\circ ({M^ + }|M)$$$$= 0.44\;V$$$$E^\circ (X|{X^ - }) = 0.33\;V$$From this data, one can deduce that

$$E{^\circ _{cell}} = - 0.77\,V$$

$${M^ + } + {X^ - } \to M + X$$ is the spontaneous reaction

$$M + X \to {M^ + } + {X^ - }$$is the spontaneous reaction

$$E{^\circ _{cell}} = .77\;V$$

## Questions 26 of 50

Question:The standard e.m.f. of a call, involving one electron change is found to be $$0.591\;V$$ at 25°C. The equilibrium constant of the reaction is ($$F = 96,500\;C\;mo{l^{ - 1}};$$ $$R = 8.314\;J{K^{ - 1}}mo{l^{ - 1}})$$

$$1.0 \times {10^{10}}$$

$$1.0 \times {10^5}$$

$$1.0 \times {10^1}$$

$$1.0 \times {10^{30}}$$

## Questions 27 of 50

Question:Standard electrode potential of cell $${H_2}|{H^ + }||A{g^ + }|Ag$$ is

0.8 V

0.8 V

1.2 V

1.2 V

## Questions 28 of 50

Question:The standard electrode potential is measured by

Electrometer

Voltmeter

Pyrometer

Galvanometer

## Questions 29 of 50

Question:Aluminium displaces hydrogen from acids but copper does not. A galvanic cell prepared by combining $$Cu/C{u^{2 + }}$$and $$Al/A{l^{3 + }}$$has an e.m.f. of 2.0 V at 298 K. If the potential of copper electrode is + 0.34 V, that of aluminium is

+ 1.66 V

1.66 V

+ 2.34 V

2.3 V

## Questions 30 of 50

Question:If the standard electrode potential of $$C{u^{2 + }}/Cu$$ electrode is 0.34V, what is the electrode potential of 0.01M concentration of $$C{u^{2 + }}$$ $$(T = 298\,K)$$

0.399 V

0.281 V

0.222 V

0.176 V

## Questions 31 of 50

Question:Which of the following compounds will not undergo decomposition on passing electricity through aqueous solution

Sugar

Sodium Chloride

Sodium Bromide

Sodium Acetate

## Questions 32 of 50

Question:During the electrolysis of an electrolyte, the number of ions produced, is directly proportional to the

Time consumed

Electro chemical equivalent of electrolysis

Quantity of electricity passed

Mass of electrons

## Questions 33 of 50

Question:In the electrolytic cell, flow of electrons is from

Cathode to anode in solution

Cathode to anode through external supply

Cathode to anode through internal supply

Anode to cathode through internal supply

## Questions 34 of 50

Question:In electrolysis of aqueous copper sulphate, the gas at anode and cathode is

$${O_2}$$ and $${H_2}$$

$$S{O_2}$$ and $${H_2}$$

$${H_2}$$ and $${O_2}$$

$$S{O_3}$$ and $${O_2}$$

## Questions 35 of 50

Question:Use of electrolysis is

Electroplating

Electrorefining

1 and 2 both

None of these

## Questions 36 of 50

Question:Sodium is made by the electrolysis of a molten mixture of about 40% $$NaCl$$ and 60% $$CaC{l_2}$$ because

$$CaC{l_2}$$ helps in conduction of electricity

This mixture has a lower melting point than $$NaCl$$

$$C{a^{ + + }}$$ can displace $$Na$$ from $$NaCl$$

$$C{a^{ + + }}$$ can reduce $$NaCl$$ to $$Na$$

## Questions 37 of 50

Question:Three faradays electricity was passed through an aqueous solution of iron (II) bromide. The weight of iron metal (at. wt. = 56) deposited at the cathode (in gm) is

56

84

112

168

## Questions 38 of 50

Question:A silver cup is plated with silver by passing 965 coulombs of electricity, the amount of silver deposited is

9.89 g

107.87 g

1.0787 g

1.002 g

## Questions 39 of 50

Question:The atomic weight of $$Al$$ is 27. When a current of 5 Faradays is passed through a solution of $$A{l^{ + + + }}$$ions, the weight of $$Al$$ deposited is

27 gm

36 gm

45 gm

39 gm

## Questions 40 of 50

Question:When 1 coulomb of charge is passed through electrolyte solution, then the mass deposited is equal to

Equivalent weight

Atomic weight

Electrochemical equivalent

Chemical equivalent

## Questions 41 of 50

Question:The platinum electrodes were immersed in a solution of cupric sulphate and electric current passed through the solution. After some time it was found that colour of copper sulphate disappeared with evolution of gas at the electrode. The colourless solution contains

Platinum sulphate

Copper hydroxide

Copper sulphate

Sulphuric acid

## Questions 42 of 50

Question:On passing $$C$$ ampere of electricity through a electrolyte solution for $$t$$ second, $$m$$gram metal deposits on cathode. The equivalent weight $$E$$ of the metal is

$$E = \frac{{C \times t}}{{m \times 96500}}$$

$$E = \frac{{C \times m}}{{t \times 96500}}$$

$$E = \frac{{96500 \times m}}{{C \times t}}$$

$$E = \frac{{C \times t \times 96500}}{m}$$

## Questions 43 of 50

Question:In a metal oxide, there is 20% oxygen by weight. Its equivalent weight is

40

64

72

32

## Questions 44 of 50

Question:On the basis of the information available from the reaction $$\frac{4}{3}Al + {O_2} \to \frac{2}{3}A{l_2}{O_3},\Delta G = - 827kJmo{l^{ - 1}}$$ of $${O_2}$$, the minimum emf required to carry out an electrolysis of $$A{l_2}{O_3}$$ is (F = 96500C $$mo{l^{ - 1}}$$)

8.56 V

2.14 V

4.28 V

6.42 V

## Questions 45 of 50

Question:The required charge for one equivalent weight of silver deposite on cathode is

$$9.65 \times {10^7}C$$

$$9.65 \times {10^4}C$$

$$9.65 \times {10^3}C$$

$$9.65 \times {10^5}C$$

## Questions 46 of 50

Question:96500 coulombs of electric current liberates from $$CuS{O_4}$$ solution

$$63.5\,gm\,Cu$$

$$31.75\,gm\,Cu$$

$$96500\,gm\,Cu$$

$$100\,gm\,Cu$$

## Questions 47 of 50

Question:On electrolysis, 1 mole of aluminium will be deposited from its molten salt by

3 moles of electrons

4 moles of electrons

2 moles of electrons

1 mole of electrons

## Questions 48 of 50

Question:The atomic weight of $$Fe$$ is 56. The weight of Fe deposited from $$FeC{l_3}$$solution by passing 0.6 Faraday of electricity is

5.6 g

11.2 g

22.4 g

33.6 g

## Questions 49 of 50

Question:In the electrolysis of water, one Faraday of electrical energy would evolve

One mole of oxygen

One g atom of oxygen

8 g of oxygen

22.4 litres of oxygen

## Questions 50 of 50

Question:In a galvanic cell, the electrons flow from