CBSE Questions for Class 12 Engineering Chemistry Electrochemistry Quiz 10 - MCQExams.com

Heated saw dust catches fire when a drop of concentrated nitric acid is added to it. This is due to
  •  dehydration
  • oxidation
  • reduction
  • dehydrogenation
Passage of three faradays of charge through an aqueous solution of $$AgNO_3, CuSO_4, Al(NO_3)_3$$ and $$NaCl$$ will deposit metals at the cathode in the molar ratio of:
  • $$1:2:3:1$$
  • $$6:3:2:6$$
  • $$6:3:0:0$$
  • $$3:2:1:0$$
Which of the following forms vortex ring?
  • $$P_2O_5$$
  • $$PH_3$$
  • $$NH_3$$
  • None of the above
On passing electricity through dil.$${ H }_{ 2 }{ SO }_{ 4 }$$ solution, the amount of substance liberated at the cathode and anode are in the ratio :
  • $$16:1$$
  • $$1:16$$
  • $$1:8$$
  • $$8:1$$
How many kgs of silver would be deposited at cathode if $$0.0342 dm^3$$ of oxygen measured at NTP is liberated at the anode when silver nitrate solution is electrolyzed between platinum electrodes?(Given : Atomic masses of Ag = 108, O =16)
  • 0.22 gm
  • 0.44 gm
  • 0.66 gm
  • None of the above
For the half reaction 
$$B(s)$$ $$\rightarrow$$ $$B^{2+} + 2e^-$$     $${ E }_{ 1 }^{ \circ  }=-0.44V$$
and 
$$B^{2+}$$ $$\rightarrow$$ $$B^{3+} + e^-$$         $${ E }_{ 2 }^{ \circ  }=1.3V$$
What is $${E}_{3}^{\circ}$$ for the reaction 
$$3e^- + B^{+3 }$$ $$\rightarrow $$ B(s):
  • $$0.86 V $$
  • $$0.14 V$$
  • $$-0.14 V $$
  • $$-0.28V$$
How much electricity in terms of Faraday is required to produce 40.0 g of $$Al$$ from molten $$Al_2O_3$$?
  • 1 Faraday
  • 2 Faraday
  • 3.2 Faraday
  • 4.44 Faraday
Which of the following will be most easily corroded in moist air?
  • $$Zn$$
  • $$Fe$$
  • $$Ni$$
  • $$Sn$$
Which among the following cell cannot be regenerated?
  • $$Ni-Cd$$ cell
  • Leclanche cell
  • All of the given
  • Lead storage cell
When an electric current is passed through acidified water, $$112\ ml$$ of hydrogen gas at $$STP$$ collects at the cathode in $$965$$ seconds. What is the current passed, in ampere?
  • $$1.0$$
  • $$0.5$$
  • $$0.1$$
  • $$2.0$$
Find the charge of $$48 g$$ of $${ Mg }^{ 2+ }$$ ions in coulombs.
  • $$2.4\times { 10 }^{ 23 }C$$
  • $$6.82\times { 10 }^{ 5 }C$$
  • $$3.86\times { 10 }^{ 5 }C$$
  • $$1.93\times { 10 }^{ 5 }C$$
The specific conductance of $$0.1N$$ $$KCl$$ solution at $${23}^{o}C$$ is $$0.012{ohm}^{-1}{cm}^{-1}$$. The resistance of cell containing the solution at the same temperature was found to be $$55$$ ohm. The cell constant will be:
  • $$0.142{cm}^{-1}$$
  • $$0.66{cm}^{-1}$$
  • $$0.918{cm}^{-1}$$
  • $$1.12{cm}^{-1}$$
Excess of silver nitrate solution is added to $$100 \,mL$$ of $$0.01 \,M$$ pentaaqua chloro chromium (III) chloride solution. The mass of silver chloride obtained in grams is: 
[Atomic mass of silver is $$108$$]
  • $$287 \times 10^{-3}$$
  • $$143.5 \times 10^{-3}$$
  • $$143.5 \times 10^{-2}$$
  • $$287 \times 10^{-2}$$
According to electrochemical theory of corrosion involves:
  • cathodic dissolution of metal
  • cathodic deposition of metal
  • anodic dissolution of metal
  • anodic deposition of metal
$$10800C$$ of electricity on passing through the electrolyte solution deposited $$2.977$$ of metal with atomic mass $${ 106.4gmol }^{ -1 }$$ the charge on the metal cation is:
  • $$+4$$
  • $$+3$$
  • $$+2$$
  • $$+1$$
Number of coulombs required to liberate 0.5 mol of $${ O }_{ 2 }$$ is:
  • 19300
  • 193000
  • 96500
  • 9650
If the density of copper is $$8.94 g/{ cm }^{ 3 }$$, the number of faradays required to plate an area $$(10cm\times 10cm)$$ of thickness of $${ 10 }^{ -2 }$$ cm using $${ CuSO }_{ 4 }$$ solution as electrolyte is:
  • $$0.1 F$$
  • $$0.28 F$$
  • $$0.4 F$$
  • $$0.5 F$$
The ratio of volume of $$H_2$$ and $$Cl_2$$ evolved at NTP by electrolysis of aqueous solution of $$HCl$$ is:
  • $$1:3$$
  • $$3:5$$
  • $$1:1$$
  • $$1:7$$
A current of 9.95 amperes flowing for 10 minutes, deposits 3g of metal. An equivalent weight of the metal is:
  • $$12.5$$
  • $$18.5$$
  • $$21.5$$
  • $$48.5$$
How many faradays are needed for reduction of 2.5 moles of $$Cr_2O_7^{2-}$$ into $$Cr^{3+}$$ ?
  • 15
  • 12
  • 6
  • 3
The standard electrode potential of the half cells is given below:
$$Zn^{2+}+2e^{-}\rightarrow Zn; E=-0.76 V$$
$$Fe^{2+}+2e^{-}\rightarrow Fe; E=-0.44 V$$
The emf of the cell $$Fe^{2+}=Zn^{-}\rightarrow Zn^{2+}+Fe $$
  • $$1.54 V$$
  • $$-1.54 V$$
  • $$0.32V$$
  • $$+0.19 V$$
Amount of charge is required to convert $$17\ g\ H_{2}O_{2}$$ into $$O_{2}$$.
  • $$1\ F$$
  • $$2\ F$$
  • $$3\ F$$
  • none of these
Given,
$$E_{Ag^{+}/Ag}^{\circ}  = +0.80V, E_{Co^{2+}/Co}^{\circ} = -0.28 V, E_{Cu^{2+}/Cu}^{\circ} = +0.34 V, E_{Zn^{2+}/Zn}^{\circ} = -0.76V$$, 
Which metal will corrode to greater extent?
  • $$Ag$$
  • $$Cu$$
  • $$Co$$
  • $$Zn$$
Identify the correct half cell reaction of the following:
$$Zn + CuSO_4 \rightarrow ZnSO_4 + Cu$$
  • $$SO_4^{2-} \rightarrow SO_4 + 2e^-$$
  • $$Zn^{2+}+2e^-\rightarrow Zn$$
  • $$Cu \rightarrow Cu^{2+} +2e^-$$
  • $$Cu^{2+} +2e^- \rightarrow Cu$$
If a pieces of iron gains $$10\%$$ of its mass due to partial rusting into $$Fe_{2}O_{3}$$ the percentage of total iron that has rusted is
  • $$3$$
  • $$13$$
  • $$23.3$$
  • $$25.67$$
For the half reaction
$$B(s) \rightarrow B^{2+} + 2e^{-}$$         $$E_{1}^{\circ} = - 0.44 V$$
and  $$B_{2}+\rightarrow B^{3+} + e^{-}$$    $$E_{2}^{\circ} = 1.3 V$$
What is $$E^{\circ}$$ for the reaction,
$$3e^{-} + B^{+3} \rightarrow B(s)$$
  • $$0.86$$ V
  • $$0.14$$ V
  • $$-0.14$$ V
  • $$-0.28$$ V
The weight in grams of $$O_2$$ formed at $$Pt$$ anode during the electrolysis of aq. $$K_2SO_4$$ solution during the passage of one coulomb of electricity is:
  • $$\dfrac{16}{96800}$$
  • $$\dfrac{8}{96500}$$
  • $$\dfrac{32}{96500}$$
  • $$\dfrac{64}{96500}$$
A current $$9.65$$ ampere is passed through the aqueous solution $$NaCl$$ using suitable electrodes for $$1000\ s$$. The amount of $$NaOH$$ formed during electrolysis is:
  • $$2.0\ g$$
  • $$4.0\ g$$
  • $$6.0\ g$$
  • $$8.0\ g$$
For the reaction:
$$F{ e }^{ 2+ }(aq)+A{ g }^{ + }(aq)\longrightarrow Ag(s)+F{ e }^{ +3 }(aq)$$

Predict which change will decrease the cell voltage?
  • Increase the amount of Ag
  • Decrease the concentration of $$A{ g }^{ + }$$
  • Increase the concentration of $$F{ e }^{ +3 }$$
  • Both $$B$$ and $$C$$
The electrolysis of aqueous solution of $$Cu{Br}_{2}$$ using platinum electrode would leads to:
  • $$Cu$$ at anode
  • $${Br}_{2}$$ gas at anode and $${O}_{2}$$ gas at cathode
  • $$Cu$$ at cathode
  • $${H}_{2}$$ gas at cathode
The number of coulombs required to deposit $$5.4 g$$ of Aluminium when the given electrode reaction is represented as $$Al^{3+}+3e^- \rightarrow Al$$.
  • $$1.83 \times 10^5C$$
  • $$57900C$$
  • $$5.86 \times 10^5 C$$
  • $$3F$$
How many faraday charge is required to convert one mole of $${C}_{6}{H}_{5}NO_{2}$$ in to $${C}_{6}H_{5}NH_{2}$$?
  • $$8$$
  • $$12$$
  • $$6$$
  • $$32$$
Given that $$ { Cl }_{ 2\left( g \right)  }+{ 2e }^{ - }\longrightarrow { 2Cl }^{ - }\left( aq \right)$$ is the reduction half-reaction for the overall reaction $$ 2Ag\left( s \right) +{ Cl }_{ 2 }\left( g \right) \longrightarrow 2AgCl\left( s \right)$$. 
What is the oxidation half reaction?
  • $$ Ag\left( s \right) \longrightarrow Ag^{ + }\left( aq \right) +e^{ - }$$
  • $$ Ag\left( s \right) +{ Cl }^{ - }\left( aq \right) \longrightarrow Ag\left( s \right) +e^{ - }$$
  • $$ Ag\left( s \right) +{ Cl }_{ 2 }\left( g \right) +e^{ - }\longrightarrow AgCl\left( s \right) +Cl^{ - }\left( aq \right)$$
  • $$ { 2Cl }^{ - }\left( aq \right) \longrightarrow { Cl }_{ 2 }\left( g \right) +2e^{ - }$$
From the following half-cell reaction and their potential, What is the smallest possible standard e.m.f spontaneous reaction?
$${ PO }_{ 4 }^{ 3- } (aq) + 2H_2O(I) + 2e^-  \longrightarrow { HPO }_{3}^{2-} + 3OH^-(aq);  E^o = -1.05 V$$
$$ PbO _2(s) + H_2O(I) + 2e^-  \longrightarrow PbO(S) + 2OH^-(aq);  E^o = +0.28 V$$
$$IO{-}{3}(aq) + 2H_2O(I) + 4e^- \longrightarrow IO^-(aq) + 4OH^-(aq);  E^o = +0.56 V$$
  • $$+0.00$$
  • $$+0.74$$
  • $$+0.56$$
  • $$+0.28$$
The time taken by the galvanic cell which operates almost ideally under reversible conditions at a current of $${ 10 }^{ -16 }$$ A to deliver 1 mole of electron is:
  • $$19.30 \times{ 10 }^{ 20 }s$$
  • $$4.825 \times{ 10 }^{ 20 }s$$
  • $$9.65 \times{ 10 }^{ 20 }s$$
  • $$3.4 \times{ 10 }^{ 11 }s$$
When molten lithium chloride $$(LiCl)$$ is electrolyzed, lithium metal is formed at the cathode. If current efficiency is $$75\%$$ then how many grams of lithium are liberated when $$1930\ C$$ of charge pass through the cell? (Atomic weight : $$Li=7$$)
  • $$0.105$$
  • $$0.120$$
  • $$0.28$$
  • $$0.240$$
Which of the following is a strong electrolyte?
  • $$ \mathrm { Ca } \left( \mathrm { NO } _ { 3 } \right) _ { 2 } $$
  • HCN
  • $$ \mathrm { H } _ { 2 } \mathrm { SO } _ { 3 } $$
  • $$ \mathrm { NH } _ { 4 } \mathrm { OH } $$
How many Faraday are required to reduce one mol of $${ MnO }_{ 4 }^{ - }$$ to $${ Mn }^{ 2+ }$$?
  • 1
  • 2
  • 3
  • 5
A schematic representation of enthalpy changes for the reaction, $${ C }_{ graphite }$$ + $$\frac { 1 }{ 2 } { O }_{ 2 }$$ (g) $$\rightarrow $$ CO (g) is given below. The missing value is
1149882_fbd603b197ea4f9a9e6372c7975a3575.png
  • + 10.5 kJ
  • - 11.05 kJ
  • - 110.5 kJ
  • - 10.5 kJ
Three faradays of electricity are passed through molten $$Al_2O_3$$, aqueous solution of $$CuSO_4$$ and molten $$NaCl$$ taken in different electrolytic cells. The amount of $$Al$$ $$Cu$$ and $$Na$$ deposited at the cathodes will be in the ratio of?
  • $$1$$ mole $$: 2$$ mole $$: 3$$ mole
  • $$3$$ mole $$: 2$$ mole $$: 1$$ mole
  • $$1$$ mole $$: 1.5$$ mole $$: 3$$ mole
  • $$1.5$$ mole $$: 2$$ mole $$: 3$$ mole
What is the charge of $$96$$ amu of $$S^{2-}$$?
  • $$2 C$$
  • $$3.2 \times 10^{-19}C$$
  • $$9.6 \times 10^{-19}C$$
  • $$6C$$
Aluminum is obtained by 
  • Heating alumina with iron
  • Heating alumina with coke
  • Electrolysis of alumina solution in molten cryolite
  • Electrolysis of fused aluminum chloride
How many Faraday charge is required for $${ KMnO }_{ 4 }\rightarrow { Mn }^{ 2+ }$$?
  • 3 F
  • 2 F
  • 5 F
  • 1 F
If the following half cells have the $$E^o$$ values as
$$Fe^{+3} + e^- \rightarrow Fe^{+2}$$; $$E^o= +0.77V$$ and $${Fe}^{+2}+2 {e}^{-} \longrightarrow {Fe}$$ ; $$E^o= -0.44 V$$ The $$E^o$$ of the half cell is $$Fe^{+3} + 3e^- \rightarrow Fe$$ will be:
  • $$0.33$$ V
  • $$1.21$$ V
  • $$0.04$$ V
  • $$0.605$$ V
When ammonia is added to a solution, its $$pH$$ is raised to $$11$$. Which half-cell reaction is affected by the $$pH$$ and by how much?
  • $$ E_{oxd} $$ will increase by a factor of $$0.65$$ from $$ E^{\circ}_{oxd} $$
  • $$ E_{oxd} $$ will decrease by a factor of $$0.65$$ from $$ E^{\circ}_{oxd} $$
  • $$ E_{red} $$ will increase by a factor of $$0.65$$ from $$ E^{\circ}_{red} $$
  • $$ E_{red} $$ will decrease by a factor of $$0.65$$ from $$ E^{\circ}_{red} $$
Electrolysis is :
  • reversible process
  • irreversible process
  • either reversible or irreversible
  • neither reversible or irreversible
Conductivity of water (in $$\Omega ^{-1}\,cm^{-1}$$) is 
  • 0.4
  • 0.04
  • 0.0004
  • 0.00004
Indicator electrode is
  • SHE
  • Calomel electrode
  • Ag/AgCl electrode
  • Quinhydrone electrode
The amount of chlorine produced per-second through electrolysis in a plate which consumes $$100$$ kW power at $$200$$V is: (Given: Electrochemical equivalent of chlorine $$=0.367\times 10^{-3}$$ g/C)
  • $$18.35$$g
  • $$1.835$$g
  • $$183.5$$g
  • $$0.1835$$g
The time required to remove electrolytically one-fourth of Ag from 0.2 litre of 0.1 M $$ AgNO_{3} $$ solution by the current of 0.1 amp is:
  • 160 min
  • 80 min
  • 40 min
  • 320 min
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