CBSE Questions for Class 12 Engineering Chemistry Electrochemistry Quiz 8 - MCQExams.com

How many electrons constitute current of one micro ampere in one second?
  • $$6.25\times10^8$$
  • $$6.25\times10^{12}$$
  • $$6.25\times10^9$$
  • $$6.25\times10^{15}$$
The weights of various ions liberated by passing the same current through different electrolytes are in the ratio of their:
  • Atomic weights
  • Equivalent weights
  • Molecular weights
  • Atomic numbers
Lead pipes are readily corroded by:
  • water
  • acetic acid
  • conc. $$H_2SO_4$$
  • dil. $$H_2SO_4$$
If copper is kept open in air, it slowly loses its shining brown surface and gains a green coating. It is due to the formation of:
  • $$CuCO_3$$
  • $$CuSO_4$$
  • $$CuCO_3.Cu(OH)_2$$
  • $$CuO$$
$$1$$ faraday $$= \ ?$$
  • $$10000\  C$$ 
  • $$95000\  C$$
  • $$96.5  \ C$$
  • $$96500\  C$$
The hydrogen formed by the action of zinc on sulphuric acid forms a layer of gas on the surface of copper plate in a simple voltaic cell, because of which
  • Internal resistance of the cell increases
  • Hydrogen ions are unable to reach the anode
  • Polarisation takes place at the anode
  • All of the above
For purification of impure metals by the process of electrolysis
  • Salt solution of the impure metal is taken as an electrolyte
  • Salt solution of that metal in pure form is taken as an electrolyte
  • That metal in pure form is made as anode
  • Both $$(1)$$ and $$(3)$$
Which of the following methods is employed to prevent rusting?
  • Refining
  • Alloying
  • Greasing
  • both (b) and (c)
During electroplating by electrolysis, the article to be electroplated is:
  • Kept immersed in the electrolyte at the bottom.
  • Made the cathode of an electrolytic cell.
  • Made the anode of an electrolytic cell.
  • Made the electrolyte of the electrolytic cell.
If $$m$$ is the mass of silver deposited at the cathode by $$2 A$$ current flowing for $$25 min$$ through a silver voltameter, then the mass deposited by $$1.5 A$$ current flowing for $$600 s$$ is _________.
  • $$m$$
  • $$3m$$
  • $$0.3m$$
  • None
The liberation of $$1$$ mole of chlorine requires how many Faradays of electricity?
  • $$0.5$$ Faraday
  • $$0.25$$ Faraday
  • $$2$$ Faradays
  • $$4$$ Faradays
In an electrolyte, $$3.2 \times 10^{18}$$ bivalent positive ions drift to the right per second while $$3.6 \times 10^{18}$$ monovalent negative ions drift to the left per second. The current through the electrolyte is _______.
  • $$0.45 A$$ to the left
  • $$0.45 A$$ to the right
  • $$1.6 A$$ to the right
  • $$1.6 A$$ to the left
The process of lead action in a simple voltaic cell
  • Catalyses the process of electrolysis
  • Increases the efficiency of the cell
  • Decreases the efficiency of the cell
  • Increases the charge carriers
The U shaped vessel used in Nelson cell is lined inside with asbestos which:
  • helps in the separation of cathode and anode compartments.
  • acts as an insulator.
  • helps $$H^{+}$$ ions to reduced to $$H_{2}$$ gas.
  • allows the dissociation of steam.
What is the voltage of the voltaic cell $$Zn|Zn^{2+}||Cu^{2+}|Cu$$ at $$298\ K$$ if $$[Zn^{2+}] = 0.2\ M$$ and $$[Cu^{2+}] = 4.0\ M$$?
$$Cu^{2+} + 2e^{-}\rightarrow Cu\ E^{\circ} = +0.34V$$
$$Zn^{2+} + 2e^{-}\rightarrow Zn\ E^{\circ} = -0.76\ V$$
[Note: $$E = E^{\circ} - (0.0591/n)(\log Q)$$
  • $$+1.10\ V$$
  • $$-1.10\ V$$
  • $$+1.07\ V$$
  • $$+1.14\ V$$
  • $$-1.07\ V$$
When current is passed through molten sodium chloride
  • sodium is deposited at the positive electrode and chlorine gas is formed at the negative electrode
  • sodium is evaporated and chloride ions and formed at the negative electrode
  • sodium is deposited at the positive electrode and chlorine is deposited at the negative electrode
  • sodium is deposited at the negative electrode and the chlorine gas is formed at the positive electrode
State True or False.

Pure water can be used as an electrolyte in the process of electrolysis.
  • True
  • False
When copper rod donates electrons to hydrogen ions, it gains ................. charge.
  • positie
  • negative
  • no charge
  • can't say
Copper electrode
  • donates electrons to hydrogen ions
  • accepts electrons from hydrogen ions
  • donates electrons to sulphate ions
  • accepts electrons from sulphate ions
In electrolytic solutions, carrier of charge is
  • proton
  • electron
  • neutron
  • ion
An electrolyte
  • has positive charge
  • has negative charge
  • should be able to conduct charge without dissociating
  • should able to form positive and negative ions
In electrolysis
  • positive ions move towards the positive electrode and negative ions towards the negative electrode.
  • positive ions move towards the negative electrode and negative ions towards the positive electrode.
  • both ions move towards both the electrodes in equal amounts until they are balanced.
  • none of the above
State True or False.

The byproducts of electrolysis of impure water are hydrogen and oxygen.
  • True
  • False
On electrolysis, water splits into
  • positively charged hydrogen ions and negatively charged oxygen ions.
  • negatively charged hydrogen ions and positively charged oxygen ions.
  • hydrogen and oxygen atoms having positive and negative charges respectively.
  • hydrogen and oxygen atoms having negative and positive charges respectively.
In the diagram above, what is the half reaction that occurs at the cathode?
491304_af8e6fed44cb48c28fbd36a8aee113f0.png
  • $$Al \rightarrow Al^{3+} + 3e^-$$
  • $$Ni^{2+} + 2e^- \rightarrow Ni$$
  • $$Ni \rightarrow Ni^{2+} + 2e^-$$
  • $$2Al^{3+} + 6e^- \rightarrow 2Al$$
  • None of these
Sulphate ions move towards
  • copper electrode
  • battery
  • electrolyte
  • zinc electrode
Electrolysis of a dilute solution of aqueous sodium chloride results in the cathode product:
  • Sodium
  • Hydrogen
  • Chlorine
  • Oxygen
  • Peroxide
For $$Cu(s) + NO_3^- (aq) + H^+(aq) \rightarrow Cu^{2+}(aq) + NO_2(g) + H_2O(l)$$, which of the following takes place?
  • $$Cu(s)$$ is oxidized
  • $$H^+ (aq)$$ is oxidized
  • $$Cu(s)$$ is reduced
  • $$H^+ (aq)$$ is reduced
  • $$NO_3^-$$ is oxidized.
Whats the potential of the reaction below given the half-reaction potentials:
$$2Fe_2+ + Cl_2 \rightarrow 2Fe^{3+} + 2Cl^-$$
$$Fe^{3+} + e^- \rightarrow Fe^{2+}; E = 0.77 V$$
$$Cl_2 + 2e^- \rightarrow 2Cl^- ; E = 1.36 V$$
  • $$0.18 V$$
  • $$0.59 V$$
  • $$1.05 V$$
  • $$2.13 V$$
  • $$2.90 V$$
In a double bond connecting two atoms there is sharing of:
  • 2 electrons
  • 4 electrons
  • 1 electron
  • none
Which of the following statements is/are not correct?
  • $$Zn-Cu$$ cell is called Daniell cell
  • Rust is $$Fe_{2}O_{3}$$
  • Saline water slows down rusting
  • Pure metals undergo corrosion faster than impure metals
I. Cathode is $$-ve$$ terminal both in electrochemical and electrolytic cells.
II. Reduction occurs at cathode both in galvanic as well as electrolytic cells.
III. Chemical change in electrolytic cell is non-spontaneous.
Which of the above statements are correct?
  • All the statements are correct
  • II and III are correct
  • I and III are correct
  • Only II is correct
In electrolysis of very dilute $$NaOH$$ solution using platinum electrodes:
  • $$H_{2}$$ is evolved at cathode
  • $$H_{2}$$ is produced at anode
  • $$Na$$ is obtained at cathode
  • $$O_{2}$$ is produced at anode
The main factors which affect corrosion are :
  • Position of metal in electrochemical series
  • Presence of $$CO_{2}$$ in water
  • Presence of impurities coating
  • All are correct
What is the sign of $$\triangle G^{\circ}$$ and the value of $$K$$ for a electrochemical cell for which $$E^{\circ}_{cell} = 0.80\ V$$?
  • $$\triangle G^{\circ} = -, K = > 1$$
  • $$\triangle G^{\circ} = +, K = > 1$$
  • $$\triangle G^{\circ} = +, K = < 1$$
  • $$\triangle G^{\circ} = -, K = < 1$$
During the electrolysis of $$AgNO_{3}$$ (using $$Pt$$ electrodes) concentration around cathode as well as anode falls from $$4M$$ to $$3M$$. What will happen if this happened with $$Ag$$ electrodes?
  • Result will remain same
  • Concentration around cathode will fall from $$4M$$ to $$3M$$ but around anode will increase from $$4M$$ to $$5M$$
  • Reverse of statement (b)
  • Concentration increases from $$4M$$ to $$5M$$ on both the electrodes
Which of the following is/are correct about 1 mole electrons?
  • $$6.023 \times 10^{23}$$ electrons
  • $$5.48 \times 10^{-7}\, kg$$
  • 96500 coulomb charge
  • None of these
The amount of charge which the battery must have been used is:
  • $$9.88\ F$$
  • $$8.98\ F$$
  • $$8.89\ F$$
  • $$7.88\ F$$
For a spontaneous reaction $$\Delta {G}^{o}$$ and $${E}^{o}$$ cell will be respectively
  • $$-ve$$ and $$+ve$$
  • $$+ve$$ and $$-ve$$
  • $$+ve$$ and $$+ve$$
  • $$-ve$$ and $$-ve$$
Pick out the pair in which the energy change of one is reverse of the energy change in the other :
(1) radio (2) fluorescent lamp (3) toaster (4) photoelectric cell
  • 1 and 2
  • 2 and 3
  • 2 and 4
  • 3 and 4
1 C electricity deposits:
  • half of electrochemical equivalent of $$Ag$$
  • electrochemical equivalent of $$Ag$$
  • 96500 g of $$Ag$$
  • 10.8 g of $$Ag$$
The mass and charge of 1 mole electrons will be:
  • 1 kg; 96500 C
  • 0.55 mg; 96500 C
  • 1.55 mg; 96500 C
  • 5.5 mg; 96500 C
In which of the following case, increase on concentration of ion cause increase in $$E_{cell}$$?
  • $$Pt(H_2)H^+(aq)$$
  • $$Pt|Quinhydrone|H^+(aq)$$
  • $$Ag|Ag^+(aq)$$
  • $$Ag, AgCl|Cl^-(aq)$$
For the above cell.
  • $$E_{cell} < 0; \triangle G > 0$$
  • $$E_{cell} > 0; \triangle G < 0$$
  • $$E_{cell} < 0; \triangle G^{\circ} > 0$$
  • $$E_{cell} > 0; \triangle G^{\circ} < 0$$
Use of electrolysis is not done in _____________.
  • production of $$Na$$
  • production of water
  • purification of metal
  • production of $$KOH$$
The standard reduction potential for $$Zn^{2+}/ Zn, Ni^{2+}/ Ni$$ and $$Fe^{2+}/ Fe$$ are $$-0.76, 0.23$$ and $$-0.44\ V$$, respectively.

The reaction, $$X + Y^{2+} \rightarrow X^{2+} + Y$$ will be spontaneous when
  • $$X = Ni, Y = Fe$$
  • $$X = Ni, Y = Zn$$
  • $$X = Fe, Y = Zn$$
  • $$X = Zn, Y = Ni$$
Which one is/ are correct among the following?
Given, the half cell emf's $$E^{0}_{Cu^{+2}/ Cu} = 0.337, E^{0}_{Cu^{+1}/ Cu} = 0.521$$.
  • $$Cu^{+1}$$ disproporationates
  • $$Cu$$ and $$Cu^{2+}$$ comproportionates (reverse of disproportionation into $$Cu^{+}$$).
  • $$E^{0}_{Cu/ Cu^{+2}} + E^{0}_{Cu^{+2}/ Cu}$$ is positive
  • All of these
$$1000\ mL\ of\ 1\ M\ CuSO_{4}(aq)$$ is electrolysed by $$9.65$$ ampere current for $$100$$ sec using $$Pt-electrode$$. Which of the following is incorrect statement?
  • Blue colour intensity decreases during electrolysis
  • Blue colour intensity remains constant if $$Cu-electrode$$ used
  • $$pH$$ of solution is $$8$$ after electrolysis
  • $$28\ mL$$ of $$CH_{4}$$ (at $$1\ atm$$ and $$273\ K)$$ undergoes combustion by $$O_{2}$$, liberated during electrolysis
In hydrogen-oxygen fuel cell the carbon rods are immersed in hot aqueous solution of.
  • $$KCl$$
  • $$KOH$$
  • $$H_2SO_4$$
  • $$NH_4Cl$$
Voltaic cell can be recharged by:
  • by addition of fresh solution
  • by replacing external circuit with external source of electricity
  • by removal of solution
  • by heating it
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