CBSE Questions for Class 12 Engineering Chemistry Electrochemistry Quiz 1 - MCQExams.com

Select among the following statements that characterize a galvanic cell?
I: Oxidation occurs at the anode, which is negative.
II: Oxidation occurs at the anode, which is positive.
III. Reduction occurs at the cathode, which is positive.
  • II only
  • III only
  • I and III
  • I, II and III
  • II and III
Assertion: The anions migrate to the cathode in an electrolytic cell.
Reason: Positively charged ions are attracted to the negatively charged cathode.
  • Both Assertion and Reason are true and Reason is the correct explanation of Assertion

  • Both Assertion and Reason are true but Reason is not the correct explanation of Assertion

  • Assertion is true but Reason is false

  • Assertion is false but Reason is true

  • Both Assertion and Reason are false

In electrochemical corrosion. the metal undergoing corrosion : 
  • acts as anode
  • acts as cathode
  • undergoes reduction
  • liquifies
Zn(s)|ZnCl$$_2$$(aq)|Cl$$^-$$(aq)|Cl$$_2$$(g)|C(s)
According to the above cell diagram the electrochemical cell described, the reaction at anode is :
  • Zn $$\rightarrow$$ Zn$$^{2+}$$ + 2e$$^-$$
  • Zn$$^{2+}$$ + 2e$$^-$$ $$\rightarrow$$ Zn
  • Cl$$_2$$ + 2e$$^-$$ $$\rightarrow$$ 2Cl$$^-$$
  • 2Cl$$^-$$ $$\rightarrow$$ Cl$$_2$$ + 2e$$^-$$
  • Zn + Cl$$_2$$ $$\rightarrow$$ ZnCl$$_2$$
$$Zn\left( s \right) \left| Zn{ Cl }_{ 2 }\left( aq \right)  \right| \left| { Cl }^{ - }\left( aq \right)  \right| \left| { Cl }_{ 2 }\left( g \right)  \right| C\left( s \right) $$
The reaction at anode in the electrochemical cell is:
  • $$Zn\rightarrow { Zn }^{ 2+ }+2e$$
  • $${ Zn }^{ 2+ }+2e\rightarrow Zn$$
  • $${ Cl }_{ 2 }+2e\rightarrow 2{ Cl }^{ - }$$
  • $$2{ Cl }^{ - }\rightarrow { Cl }_{ 2 }+2e$$
  • $$Zn+{ Cl }_{ 2 }\rightarrow Zn{ Cl }_{ 2 }$$
What is a cathode?
  • Electrode where reduction takes place and electrons are gained.
  • Electrode where oxidation takes place and electrons are lost.
  • Electrode where reduction takes place and electrons are lost.
  • A fluid that conducts electricity.
  • Electrode where oxidation takes place and electrons are gained.
Which half-cell reactions describes what is going on at the anode, from the diagram ?

482776.png
  • $$Zn\rightarrow Zn^{2+} + 2e^{-}$$
  • $$H_{2} \rightarrow 2H^{+} + 2e^{-}$$
  • $$2Cl^{-} \rightarrow Cl_{2} + 2e^{-}$$
  • $$SO^{4-} \rightarrow S + 2O2 + 6e^{-}$$
  • $$2H^{+} + 2e^{-} \rightarrow H_{2}$$
What is the correct formula for determining the voltage of an electrochemical cell?
  • $$E^{0}_{cell}$$ = $$E^{0}_{cathode}$$  - $$E^{0}_{anode}$$
  • $$E^{0}_{cell}$$ = $$E^{0}_{cathode}$$  + $$E^{0}_{anode}$$
  • $$E^{0}_{constant}$$ = $$E^{0}_{cathode}$$  - $$E^{0}_{anode}$$
  • $$E^{0}_{constant}$$ = $$E^{0}_{cathode}$$  + $$E^{0}_{anode}$$
  • $$E^{0}_{cell}$$ = -$$E^{0}_{cathode}$$  + $$E^{0}_{anode}$$
What two metals are often used in electrochemical cells?
  • Zinc and copper
  • Zinc and sulfur
  • Carbon and copper
  • Zinc and carbon
  • Sulfur and copper
At anode of an electrochemical cell, which of the following change may occur?
  • $$\displaystyle { Cu }^{ 2+ }$$ to $$\displaystyle Cu$$
  • $$\displaystyle Cl{ O }_{ 3 }^{ - }$$ to $$\displaystyle Cl{ O }^{ - }$$
  • $$\displaystyle { Cl }^{ - }$$ to $$\displaystyle { Cl }_{ 2 }$$
  • $$\displaystyle { H }^{ + }$$ to $$\displaystyle { H }_{ 2 }$$
  • $$\displaystyle { O }_{ 2 }$$ to $$\displaystyle { H }_{ 2 }O$$
Which of the following will not occur in a voltaic cell while a chemical reaction is on a spontaneous process?
  • The electrons will migrate through the wire
  • The cations in the salt bridge will migrate to the anode half-cell
  • The cathode will gain mass
  • The anode will lose mass
  • Reduction will occur at the cathode
What is corrosion?
  • When metal is gradually destroyed through chemical reactions
  • When metal is created through chemical reactions
  • When a redox reaction takes place
  • When a metal is destroyed after exposure to a gas
  • When a solid is destroyed through chemical reactions
Assertion: Input of energy is required by electrolytic cells.
Reason: Electrolytic cells have just one container, while voltaic cells have two.
  • Both Assertion and Reason are true and Reason is the correct explanation of Assertion
  • Both Assertion and Reason are true but Reason is not the correct explanation of Assertion
  • Assertion is true but Reason is false
  • Assertion is false but Reason is true
  • Both Assertion and Reason are false
For the following reactions:
$$Zn \rightarrow Zn^{2+} + 2e^-; E=+0.76 V$$
$$Au \rightarrow Au^{3+} + 3e^-; E=-1.42 V$$
If gold foil is placed in a solution containing $$Zn^{2+}$$, the reaction potential would be:
  • $$-1.34 V$$
  • $$-2.18 V$$
  • $$-0.66 V$$
  • $$+2.18 V$$
  • $$+1.34 V$$
Which of these statements best describes a galvanic cell?
  • Reduction occurs at the anode.
  • Oxidation occurs at the anode.
  • Energy is required from an external source.
  • The thode is negative.
  • $$E^o_{cell}$$ is negative.
Electrolysis of water to form hydrogen and oxygen gas is called __________.
  • precipitation
  • oxidation-reduction
  • distillation
  • hydration
  • condensation
Which of the following is true for an electrolytic cell?
  • An electric current causes an otherwise nonspontanteous chemical reaction to occur.
  • Reduction occurs at the anode.
  • A spontaneous electrochemical reaction produces an electric current.
  • The electrode to which electrons flow is where oxidation occurs.
  • None of the above
A battery  jar contained a solution of copper sulfate. Two electrodes. one made of copper the other a metal object to be copper plated, were placed in the jar and connected to a source of direct current. Which of the following statements concerning this system is correct?
  • The object to be placed is the anode
  • Oxidation occurs at the anode
  • The sulfate ions migrate toward the cathode
  • The concentration of the copper sulfate solution increases as electrolysis proceeds
  • The copper electrode increases in mass.
In the electrolysis of molten copper chloride, the substance liberated at the anode is __________ .
  • copper
  • chlorine
  • hydrogen
  • copper chloride
  • none of the above
Choose the correct statement from the following:
  • Cations move towards cathode during the process of electrolysis
  • Electrolysis is the process of decomposition of a electrolyte by the action of electric currrent
  • SI unit of chemical equivalent is kg
  • One faraday = 96500 coulombs
In the electrochemical cell shown above, which of the following half-reactions occurs at the anode?
524234.JPG
  • $$\displaystyle { Cu }^{ 2+ }+e\rightarrow { Cu }^{ - }$$
  • $$\displaystyle Zn\left( s \right) \rightarrow { Zn }^{ 2+ }+2e$$
  • $$\displaystyle { Zn }^{ 2+ }+2e\rightarrow Zn\left( s \right) $$
  • $$\displaystyle Cu\left( s \right) \rightarrow { Cu }^{ 2+ }+2e$$
  • $$\displaystyle { Cu }^{ 2+ }+2e\rightarrow Cu\left( s \right) $$
    $$\displaystyle $$
Which of these half-reactions represents an oxidation?
I. $$Sn^{4+} \rightarrow  Sn^{2+}$$
II. $$MnO_4^-\rightarrow Mn^{2+}$$
III. $$Cl_2\rightarrow ClO_3^-$$
  • I only
  • II only
  • III only
  • I and II only
  • II and III only
An iron nail, solid iron metal, rusts. What type of reaction is it?
  • Decomposition
  • Synthesis
  • Combustion
  • Single replacement
A secondary cell is one that :
  • can be recharged
  • can be recharged by passing current through it in the same direction
  • can be recharged by passing current through it in the opposite direction
  • can not be recharged
In the galvanic cell :
$$Zn/Zn^{2+} (C_1)||Cu^{2+} (C_2)/Cu$$
$$E_{cell} - E_{cell}^o = +0.0591 V$$. The value of $$\dfrac{C_1}{C_2}$$ at $$298\ K$$ is:
  • $$10^{-1}$$
  • $$10^{2}$$
  • $$10^{-2}$$
  • $$10$$
Which expression gives the correct value for the standard potential for a gold-rhodium voltaic cell?
Half-reaction$$E^{\circ}(V)$$
$$Rh_{(aq)}^{+3} + 3e^{-} \rightarrow Rh_{(s)}$$$$0.76\ V$$
$$Au_{(aq)}^{+} + e^{-} \rightarrow Au_{(s)}$$$$1.69\ V$$
  • $$1.69\ V + 0.76\ V$$
  • $$1.69\ V - 0.76\ V$$
  • $$3(1.69)\ V + 0.76\ V$$
  • $$3(1.69)\ V - 0.76\ V$$
_________ is an application of electrolysis.
  • Oxidation
  • Electrotyping
  • Electric shielding
  • Electric polishing.
During electrolysis negative terminal used is called anode.
  • True
  • False
State True or False.
In an electrochemical cell, in the inner circuit current is carried by ions and in the external circuit, current of electrons flows through the metal conductors.
  • True
  • False
Splitting a compound using electricity is called:
  • electrolysis
  • electrolyte
  • electrokinesis
  • none of the above
In electrolysis, mass of the substance liberated at cathode is proportional to 
  • strength of the current passed.
  • time of passage of current.
  • quantity of electricity passed.
  • none of these
Examine the drawing of an electrolytic cell shown:

Determine the time it would take to plate $$10.0\ g\ Ag$$ with a current of $$0.452A$$.

536558_5cd513d8b9594a47b82ab5c5167bda4a.jpg
  • $$2.5\ hr$$
  • $$3.5\ hr$$
  • $$4.5\ hr$$
  • $$5.5\ hr$$
Which of the following represents the oxidation half-reaction for the unbalanced redox equation?
$$Cu + HNO_{3} \rightarrow Cu (NO_{3})_{2} + NO_{2}$$
  • $$Cu^{2+} + 2e^{-} \rightarrow Cu$$
  • $$Cu \rightarrow Cu^{2+} + 2e^{-}$$
  • $$NO_{3}^{-} \rightarrow NO_{2} + 1e^{-}$$
  • $$2H^{+} + NO_{2}^{-} + 1e^{-} \rightarrow NO_{2} + H_{2}O$$
If the $${ E }_{ cell }^{ o }$$ for a given reaction has a negative value then which of the following gives the correct relationships for the values of $$\Delta { G }^{ o }$$ and $${ K }_{ eq }$$?
  • $$\Delta { G }^{ o } < 0; { K }_{ eq } > 1$$
  • $$\Delta { G }^{ o } < 0; { K }_{ eq } < 1$$
  • $$\Delta { G }^{ o } > 0; { K }_{ eq } < 1$$
  • $$\Delta { G }^{ o } > 0; { K }_{ eq } > 1$$
The number of moles of electrons required to discharge one mole of $$Al^{3+}$$ is:
  • $$3$$
  • $$1$$
  • $$2$$
  • $$4$$
Electrochemical equivalent is the amount of substance which gets deposited from its solution on passing electrical charge equal to :
  • $$96,500$$ coulomb
  • $$1$$ coulomb
  • $$60$$ coulomb
  • $$965$$ coulomb
The breaking down of a compound by passing electricity through it is known as
    • electromagnetism
    • electrolysis
    • electronics
    • ultrasound
    Who invented the first true battery ?
    • Faraday
    • Ohm
    • Volta
    • Alva Edison
    What is used as anode in Volta's cell?
    • Zinc plate
    • Copper plate
    • Carbon rod
    • Iron plate
    In three test tubes $$P, Q$$, and $$R$$ iron nails, water, oil and anhydrous calcium chloride is taken. Among these test tubes, in which test tubes corrosion of nails will not take place?
    625391_18ea6dcaf8924ec686715f138a594897.png
    • $$P, Q$$ and $$R$$
    • $$P$$ and $$R$$
    • $$P$$ and $$Q$$
    • $$Q$$ and $$R$$
    How many faradays are required to reduce 1 mol of $$Cr_2O_7^{2-}$$ to $$Cr^{3+}$$ in acidic medium?
    • 2
    • 3
    • 5
    • 6
    The equilibrium constant of the reaction;
    $$Cu\left( s \right) +2{ Ag }^{ + }\left( aq \right) \longrightarrow { Cu }^{ 2+ }\left( aq \right) +2Ag\left( s \right) $$
    $${ E }^{ o }=0.46V$$ at $$298 K$$
    • $$2.4\times { 10 }^{ 10 }$$
    • $$2.0\times { 10 }^{ 10 }$$
    • $$4.0\times { 10 }^{ 10 }$$
    • $$4.0\times { 10 }^{ 15 }$$
    Conductivity of a solution is  affected by:
    • addition of water
    • process of heating
    • addition of acetic acid
    • all of the above
    When metals corrodes, it is being :
    • dissolved into surrounding moisture
    • weakened structurally
    • chemically combined with another metal
    • reacted with oxygen
    Number of faradays' required to generate one gram atom of magnesium from molten $$MgCl_{2}$$ is_________.
    • $$1$$
    • $$2$$
    • $$3$$
    • $$4$$
    $$K, Ca$$ and $$Li$$ metals may be arranged in the decreasing order of their standard electrode potentials as____________.
    • $$K, Ca$$ and $$Li$$
    • $$Li, K$$ and $$Ca$$
    • $$Li, Ca$$ and $$K$$
    • $$Ca, Li$$ and $$K$$
    A solution of sodium sulphate in water is electrolysed using platinum electrodes. The products at cathode and anode are respectively:
    • $$H_{2}, O_{2}$$
    • $$O_{2}, H_{2}$$
    • $$O_{2}, Na$$
    • $$O_{2}, SO_{2}$$
    Three faradays of electricity was passed through an aqueous solution of iron(II) bromide. The mass of iron metal (At. mass $$56$$) deposited at the cathode is:
    • $$56\ g$$
    • $$84\ g$$
    • $$112\ g$$
    • $$168\ g$$
    The half-cell reaction is the one that:
    • takes place at one electrode
    • consumes half a unit of electricity
    • involves half a mole of electrolyte
    • goes half way to completion
    One Faraday is equal to:
    • $$9650\ coulomb$$
    • $$10,000\ coulomb$$
    • $$19640\ coulomb$$
    • $$96500\ coulomb$$
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