# Electrochemistry Test 7

Total Questions:50 Total Time: 75 Min

Remaining:

## Questions 1 of 50

Question:If the half cell reaction $$A + {e^ - } \to \,{A^ - }$$ has a large negative reduction potential, it follows that

$$A$$ is readily reduced

$$A$$ is readily oxidized

$${A^ - }$$ is readily reduced

$${A^ - }$$ is readily oxidised

## Questions 2 of 50

Question:Mark the false statement

A salt bridge is used to eliminate liquid junction potential

The Gibbs free energy change, $$\Delta G$$ is related with electromotive force $$(E)$$, as $$\Delta G = - nFE$$

Nernst equation for single electrode potential is $$E = {E^o} - \frac{{RT}}{{nF}}\,\ln \,{a_{{M^{n + }}}}$$

The efficiency of a hydrogen oxygen fuel cell is 23%

## Questions 3 of 50

Question:Which of the following statements is correct ? Galvanic cell converts

Chemical energy into electrical energy

Electrical energy into chemical energy

Metal from its elemental state to the combined state

Electrolyte into individual ions

## Questions 4 of 50

Question:Hydrogen–oxygen fuel cells are used in space–craft to supply

Power for heat and light

Power for pressure

Oxygen

Water

## Questions 5 of 50

Question:The anode half-reaction occurring during the discharge of a lead storage battery is

$$Pb(s) + S{O_2} + {O_2} \to PbS{O_4}(s)$$

$$Pb(s) + SO_4^{2 - }(aq)$$?$$PbS{O_4}(s) + 2{e^ - }$$

$$Pb{O_2}(s) + 4{H^ + }(aq) + 2{e^ - } + SO_4^{2 - }(aq)$$? $$PbS{O_4}(s) + 2{H_2}O$$

$$P{b^{2 + }}(aq) + SO_4^{2 - }(aq) \to PbS{O_4}(s)$$

## Questions 6 of 50

Question:The unit of cell constant is

$$oh{m^{ - 1}}\,c{m^{ - 1}}$$

$$ohm\,cm$$

$$cm$$

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

## Questions 7 of 50

Question:Which of the following statement is true for the electrochemical Daniel cell

Electrons flow from copper electrode to zinc electrode

Current flows from zinc electrode to copper electrode

Cations move toward copper electrode which is cathode

Cations move toward zinc electrode

## Questions 8 of 50

Question:Which of the following statement is true for an electrochemical cell

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

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

Reduction occurs at $${H_2}$$electrode

Oxidation occurs at Cu electrode

## Questions 9 of 50

Question:The conductivity of strong electrolyte is

Increase on dilution slightly

Decrease on dilution

Does not change with dilution

Depend upon density of electrolytes itself

## Questions 10 of 50

Question:If X is the specific resistance of the solution and M is the molarity of the solution, the molar conductivity of the solution is given by

$$\frac{{1000X}}{M}$$

$$\frac{{1000}}{{MX}}$$

$$\frac{{1000M}}{X}$$

$$\frac{{MX}}{{1000}}$$

## Questions 11 of 50

Question:Which of the following is a poor conductor of electricity

$$C{H_3}COONa$$

$${C_2}{H_5}OH$$

$$NaCl$$

$$KOH$$

## Questions 12 of 50

Question:The molar conductivity is maximum for the solution of concentration

0.001 M

0.005 M

0.002 M

0.004 M

## Questions 13 of 50

Question:A solution containing one mole per litre of each $$Cu{(N{O_3})_2},\,\,AgN{O_3},\,\,H{g_2}{(N{O_3})_2}$$ and $$Mg{(N{O_3})_2},$$ is being electrolysed by using inert electrodes. The values of standard electrode potentials in volts (reduction potentials) are $$Ag/A{g^ + } = + 0.80,\,\,2Hg/Hg_2^{2 + } = + 0.79,\,\,Cu/C{u^{2 + }} = + 0.34,$$$$Mg/M{g^{2 + }} = - 2.37$$with increasing voltage, the sequence of deposition of metals on the cathode will be

$$Ag,\,\,Hg,\,\,Cu,\,\,Mg$$

$$Mg,\,\,Cu,\,\,Hg,\,\,Ag$$

$$Ag,\,\,Hg,\,\,Cu$$

$$Cu,\,\,Hg,\,\,Ag$$

## Questions 14 of 50

Question:The standard reduction electrode potentials of four elements are $$A = - 0.250\,\,V$$$$B = - 0.136\,V$$ $$C = - 0.126\,\,V$$$$D = - 0.402\,\,V$$. The element that displaces A from its compounds is

B

C

D

None of these

## Questions 15 of 50

Question:$$K,\,\,Ca$$ and $$Li$$ metals may be arranged in the decreasing order of their standard electrode potentials as

$$K,\,\,Ca,\,\,Li$$

$$Ca,\,\,K,\,\,Li$$

$$Li,\,\,Ca,\,\,K$$

$$Ca,\,\,Li,\,\,K$$

## Questions 16 of 50

Question:The correct order of chemical reactivity with water according to electrochemical series

$$K > Mg > Zn > Cu$$

$$Mg > Zn > Cu > K$$

$$K > Zn > Mg > Cu$$

$$Cu > Zn > Mg > K$$

## Questions 17 of 50

Question:Adding powdered lead and iron to a solution that is 1.0 M in both $$P{b^{2 + }}$$and $$F{e^{2 + }}$$ions, would result a reaction, in which

More iron and $$P{b^{2 + }}$$ions are formed

More lead and $$F{e^{2 + }}$$ions are formed

Concentration of both $$P{b^{2 + }}$$and $$F{e^{2 + }}$$ions increases

There is no net change

## Questions 18 of 50

Question:Given standard electrode potentials $$F{e^{ + + }} + 2{e^ - }\, \to \,Fe\,;\,\,\,\,{E^o} = - 0.440\,\,V$$, $$F{e^{ + + + }} + 3{e^ - }\, \to \,Fe\,;\,\,\,\,{E^o} = - 0.036\,\,V$$. The standard electrode potential $$({E^o})$$ for $$F{e^{ + + + }} + {e^ - } \to \,F{e^{ + + }}$$ is

0.476 V

0.404 V

+ 0.404 V

+ 0.771 V

## Questions 19 of 50

Question:In which cell the free energy of a chemical reaction is directly converted into electricity ?

Leclanche cell

Concentration cell

Fuel cell

## Questions 20 of 50

Question:Nernst equation is related with

The electrode potential and concentration of ions in the solution

Equilibrium constant and concentration of ions

Free energy change and E.M.F. of the cell

None of these

## Questions 21 of 50

Question:What is $${E^o}$$ for electrode represented by $$Pt,\,{O_2}(1\,atm)\,/\,2{H^ + }({\mathop{\rm Im}\nolimits} )$$

Unpredictable

Zero

0.018 V

0.118 V

## Questions 22 of 50

Question:The cell potential of a cell in operation is

Zero

Positive

Negative

None of the above

## Questions 23 of 50

Question:EMF of a cell in terms of reduction potential of its left and right electrodes is

$$E = {E_{left}} - {E_{right}}$$

$$E = {E_{left}} + {E_{right}}$$

$$E = {E_{right}} - {E_{left}}$$

$$E = - ({E_{right}} + {E_{left}})$$

## Questions 24 of 50

Question:Arrange the following in the order of their decreasing electrode potential Mg, K, Ba, Ca

$$K,Ba,Ca,Mg$$

$$Ca,Mg,K,Ba$$

$$Ba,Ca,K,Mg$$

$$Mg,Ca,Ba,K$$

## Questions 25 of 50

Question:The emf of a galvanic cell, with electrode potentials of silver = +0.80V and that of copper = + 0.34 V, is

1.1 V

+ 1.1 V

+ 0.46 V

+ 0.76 V

## Questions 26 of 50

Question:Copper cannot replace….. from solution

$$Fe$$

$$Au$$

$$Hg$$

$$Ag$$

## Questions 27 of 50

Question:Consider the following $${E^0}$$values : $${E^0}_{F{e^{3 + }}/F{e^{2 + }}}$$ =$$+ 0.77\;V$$, $${E^0}_{S{n^{2 + }}/Sn} = - 0.14\;V$$. Under standard conditions the potential for the reaction $$S{n_{(s)}} + 2F{e^{3 + }}(aq) \to 2F{e^{2 + }}(sq) + S{n^{2 + }}(aq)$$ is

0.91 V

1.40 V

1.68 V

0.63 V

## Questions 28 of 50

Question:$$C{r_2}O_7^{2 - } + {I^ - } \to {I_2} + C{r^{3 + }}$$, $${E^0}_{cell} = 0.79\;V$$, $$E_{C{r_2}O_7^{2 - }}^0 = 1.33\;V,\;{E^0}_{{I_2}}$$ is

$$- 0.10\;V$$

$$+ 0.18\;V$$

$$- 0.54\;V$$

$$0.54\;V$$

## Questions 29 of 50

Question:An electrolyte

Forms complex ions in solution

Gives ions only when electricity is passed

Possesses ions even in solid state

Gives ions only when dissolved in water

## Questions 30 of 50

Question:Electrolytes when dissolved in water dissociates into ions because

They are unstable

The water dissolves it

The force of repulsion increases

The forces of electrostatic attraction are broken down by water

## Questions 31 of 50

Question:Electrolyte can conduct electricity because

Their molecules contain unpaired electrons, which are mobile

Their molecules contain loosely held electrons which get free under the influence of voltage

The molecules break up into ions when a voltage is applied

The molecules are broken up into ions when the electrolyte is fused or is dissolved in the solvent

## Questions 32 of 50

Question:The amount of ion discharged during electrolysis is not directly proportional to

Resistance

Time

Current

Chemical equivalent of the ion

## Questions 33 of 50

Question:Electrolysis of aqueous $$HCl$$ solution produces

$${H_2}$$ gas at the anode

$${H_2}$$ gas at the cathode

$$C{l_2}$$ gas at the cathode

$$C{l_2}$$ and $${O_2}$$ gases both at the anode

## Questions 34 of 50

Question:During electrolysis of $$NaCl$$solution, part of the reaction is $$N{a^ + } + {e^ - } \to Na.$$ This is termed as

Oxidation

Reduction

Deposition

Cathode reaction

## Questions 35 of 50

Question:Which of the following properties of pure metal makes it more useful then the corresponding alloy

It is harder than corresponding alloy

It has high density

It can be extracted easily

It conducts heat and electricity easily

## Questions 36 of 50

Question:Which of the following liberate hydrogen on reaction with dilute $${H_2}S{O_4}$$

$$Fe$$

$$Cu$$

$$Al$$

$$Hg$$

## Questions 37 of 50

Question:Which one of the following material conducts electricity

Diamond

Crystalline sodium chloride

Barium sulphate

Fused potassium chloride

Molten sulphur

## Questions 38 of 50

Question:On passing 0.1 Faraday of electricity through aluminium chloride, the amount of aluminium metal deposited on cathode is $$(Al = 27)$$

0.9 gm

0.3 gm

0.27 gm

2.7 gm

## Questions 39 of 50

Question:Which of the following represents the first law of Faraday

$$E = m{c^2}$$

$$E = hv$$

$$m = ect$$

$$PV = nRT$$

## Questions 40 of 50

Question:5 amperes is passed through a solution of zinc sulphate for 40 minutes. Find the amount of zinc deposited at the cathode

40.65 gm

4.065 gm

0.4065 gm

65.04 gm

## Questions 41 of 50

Question:A current 2.0 A is passed for 5 hours through a molten metal salt deposits 22 g of metal (At. wt. =177). The oxidation state of the metal in the metal salt is

1

2

3

4

## Questions 42 of 50

Question:How many atoms of calcium will be deposited from a solution of $$CaC{l_2}$$ by a current of 25 milliamperes flowing for 60 seconds

$$4.68 \times {10^{18}}$$

$$4.68 \times {10^{15}}$$

$$4.68 \times {10^{12}}$$

$$4.68 \times {10^9}$$

## Questions 43 of 50

Question:Faraday's laws of electrolysis are related to the

Atomic number of cation

Atomic number of anion

Equivalent weight of the electrolyte

Speed of the cation

## Questions 44 of 50

Question:The electric charge for electrode decomposition of one gram equivalent of a substance is

One ampere per second

96500 coulombs per second

One ampere for one hour

Charge on one mole of electrons

## Questions 45 of 50

Question:When electricity is passed through the solution of $$AlC{l_3},\,\,13.5\,\,gm$$ of $$Al$$ are deposited. The number of Faraday must be

0.5

1

1.5

2

## Questions 46 of 50

Question:The value of one Faraday is

$$95500\,\,C\,\,mo{l^{ - 1}}$$

$$96550\,\,C\,\,mo{l^{ - 1}}$$

$$96500\,\,C\,\,mo{l^{ - 1}}$$

$$98500\,\,C\,\,mo{l^{ - 1}}$$

## Questions 47 of 50

Question:The unit for the electric current is

Ohm

Volt

Ampere

Coulomb

## Questions 48 of 50

Question:The quantity of electricity required to liberate $$112\,\,\,c{m^3}$$ of hydrogen at STP from acidified water is

965 Coulomb

96500 Coulomb

## Questions 49 of 50

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

56 $$c{m^3}$$

550 $$c{m^3}$$

5.6 $$c{m^3}$$

11.2 $$c{m^3}$$

22.4 $$c{m^3}$$

## Questions 50 of 50

Question:During electrolysis of aqueous $$NaOH,\,4\,g$$ of $${O_2}$$ gas is liberated at $$NTP$$ at anode, $${H_2}$$ gas liberated at cathode is