Advanced Problems in Physical Chemistry for Competitive Examinations

Neeraj Kumar

Chapter 8

Electrochemistry - all with Video Answers

Educators

Section 1

Exercises I

Problem 1

A metal rod is dipped in a solution of its ions. Its electrode potential is independent of
(a) temperature of the solution
(b) concentration of the solution
(c) area of the metal exposed Id

Shahina -

Shahina -

Numerade Educator

Problem 2

Indicator electrode is
(a) SHE
(b) Calomel electrode
(c) $\mathrm{Ag} / \mathrm{AgCl}$ electrode
(d) Quinhydrone electrode

Shahina -

Numerade Educator

Problem 3

The position of some metals in the electrochemical series in decreasing electropositive character is given as:
$\mathrm{Mg}>\mathrm{Al}>\mathrm{Zn}>\mathrm{Cu}>\mathrm{Ag} .$ What will
happen if a copper spoon is used to stira solution of aluminium nitrate?
(a) The spoon will get coated with aluminium.
(b) An alloy of copper and aluminium is formed.
(c) The solution becomes blue.
(d) No chemical change will take place.

Shahina -

Numerade Educator

Problem 4

Four colourless salt solutions are placed in separate test tubes and a strip of copper is placed in each. Which solution finally turns blue?
(a) $\mathrm{AgNO}_{3}$
(b) $\mathrm{Pb}\left(\mathrm{NO}_{3}\right)_{2}$
(c) $\mathrm{Zn}\left(\mathrm{NO}_{3}\right)_{2}$
(d) $\mathrm{Cd}\left(\mathrm{NO}_{3}\right)_{2}$

Shahina -

Numerade Educator

Problem 5

The metal that cannot be obtained on reduction of its oxide by aluminium is
(a) $\mathrm{K}$
(b) $\mathrm{Mn}$
(c) $\overline{\mathrm{Cr}}$
(d) $\mathrm{Fe}$

Shahina -

Numerade Educator

Problem 6

Beryllium is placed above magnesium in the group II. Beryllium dust, therefore, when added to $\mathrm{MgCl}_{2}$ solution will
(a) have no effect
(b) precipitate $\mathrm{Mg}$ metal
(c) precipitate $\mathrm{MgO}$
(d) lead to dissolution of Be metal

Shahina -

Numerade Educator

Problem 7

A standard hydrogen electrode has zero electrode potential because
(a) hydrogen is easiest to oxidize
(b) this electrode potential is assumed to be zero
(c) hydrogen atom has only one electron
(d) hydrogen is the lightest element

Shahina -

Numerade Educator

Problem 8

The standard reduction potential values of three metallic cations, $\mathrm{X}, \mathrm{Y}$ and $Z$ are $+0.52,-3.03$ and $-1.18 \mathrm{~V}$, respectively.
The order of reducing power of the corresponding metals is
(a) $\mathrm{Y}>\mathrm{Z}>\mathrm{X}$
(b) $\mathrm{X}>\mathrm{Y}>\mathrm{Z}$
(c) $\mathrm{Z}>\mathrm{Y}>\mathrm{X}$
(d) $Z>X>Y$

Shahina -

Numerade Educator

Problem 9

A gas ' $X$ ' at 1 atm is bubbled through a solution containing a mixture of $1 \mathrm{M}$ $-\mathrm{Y}^{-}$ and $1 \mathrm{M}-\mathrm{Z}^{-}$ at $25^{\circ} \mathrm{C}$. If the reduction potential of $Z>Y>X$, then.
(a) $\mathrm{Y}$ will oxidize $\mathrm{X}$ and $\mathrm{not} \mathrm{Z}$
(b) $\mathrm{Y}$ will oxidize $\mathrm{Z}$ and $\mathrm{not} \mathrm{X}$
(c) $Y$ will oxidize both $X$ and $Z$
(d) $\mathrm{Y}$ will reduce both $\mathrm{X}$ and $\mathrm{Z}$

Shahina -

Numerade Educator

Problem 10

Standard electrode potential data are useful for understanding the suitability of an oxidant in a redox titration. Some half-cell reactions and their standard potentials are given below:

Shahina -

Numerade Educator

Problem 11

The decreasing order of standard electrode potential of $\mathrm{Mg}, \mathrm{K}, \mathrm{Ba}$ and $\mathrm{Ca}$, is
(a) $\mathrm{K}, \mathrm{Ca}, \mathrm{Ba}, \mathrm{Mg}$
(b) $\mathrm{Ba}, \mathrm{Ca}, \mathrm{K}, \mathrm{Mg}$
(c) $\mathrm{Ca}, \mathrm{Mg}, \mathrm{K}, \mathrm{Ba}$
(d) $\mathrm{Mg}, \mathrm{Ca}, \mathrm{Ba}, \mathrm{K}$

Shahina -

Numerade Educator

Problem 12

A metal having negative reduction potential, when dipped in the solution of its own ions, has a tendency to
(a) remain as metal atoms
(b) become electrically positive
(c) become electrically negative
(d) be deposited from the solution

Bridger Johnston

Bridger Johnston

Numerade Educator

Problem 13

The calomel electrode is reversible with respect to
(a) $\mathrm{Hg}_{2}^{2+}$
(b) $\mathrm{H}^{+}$
(c) $\mathrm{Hg}^{2+}$
(d) $\mathrm{Cl}$

Shahina -

Numerade Educator

Problem 14

Which one of the following does not get oxidized by bromine water?
(a) $\mathrm{Fe}^{2+}$ to $\mathrm{Fe}^{3+}$
(b) $\mathrm{Cu}^{+}$ to $\mathrm{Cu}^{2+}$
(c) $\mathrm{Mn}^{2+}$ to $\mathrm{MnO}_{4}^{-}$
(d) $\mathrm{Sn}^{2+}$ to $\mathrm{Sn}^{4+}$

Shahina -

Numerade Educator

Problem 15

In salt bridge, normally $\mathrm{KCl}$ is used because
(a) it is a strong electrolyte.
(b) it is good conductor of electricity.
(c) $\mathrm{K}^{+}$ and $\mathrm{Cl}^{-}$ ions have nearly same ionic mobility.
(d) it is an ionic compound.

Shahina -

Numerade Educator

Problem 16

By how much would the oxidizing power of $\mathrm{MnO}_{4}^{-} / \mathrm{Mn}^{2+}$ couple change if the $\mathrm{H}^{\circ}$
ions concentration is decreased 100 times at $25^{\circ} \mathrm{C}$ ?
(a) increases by $189 \mathrm{mV}$
(b) decreases by $189 \mathrm{mV}$
(c) will increase by $19 \mathrm{mV}$
(d) will decrease by $19 \mathrm{mV}$

Hast Aggarwal

Numerade Educator

Problem 17

The solution of $\mathrm{CuSO}_{4}$, in which copper rod is immersed, is diluted to 10 times. The reduction electrode potential
(a) increases by $0.0295 \mathrm{~V}$
(b) decreases by $0.0295 \mathrm{~V}$
(c) increases by $0.059 \mathrm{~V}$
(d) decreases by $0.059 \mathrm{~V}$

Shahina -

Numerade Educator

Problem 18

The standard reduction potential of oxygen in acidic solution is $+1.23 \mathrm{~V}$. What is the standard reduction potential of oxygen in basic solution?
(a) $+0.404 \mathrm{~V}$
(b) $-0.404 \mathrm{~V}$
(c) $+2.056 \mathrm{~V}$
(d) $-2.056 \mathrm{~V}$

Himanshu Kushwaha

Himanshu Kushwaha

Numerade Educator

Problem 19

The standard reduction potentials of $\mathrm{Cu}^{2+} \mid \mathrm{Cu}$ and $\mathrm{Cu}^{2+} \mid \mathrm{Cu}^{+}$ are $0.337 \mathrm{~V}$
and $0.153 \mathrm{~V}$, respectively. The standard electrode potential of $\mathrm{Cu}^{+} \mid$ Cu half-cell is
(a) $0.184 \mathrm{~V}$
(b) $0.827 \mathrm{~V}$
(c) $0.521 \mathrm{~V}$
(d) $0.490 \mathrm{~V}$

Hast Aggarwal

Numerade Educator

Problem 20

The electrode potential of hydrogen electrode in neutral solution and $298 \mathrm{~K}$ is
(a) $-0.413 \mathrm{~V}$
(b) zero
(c) $-0.826 \mathrm{~V}$
(d) $+0.413 \mathrm{~V}$

Himanshu Kushwaha

Himanshu Kushwaha

Numerade Educator

Problem 21

Electrode potential will be more for hydrogen electrode at $\mathrm{pH}$ (at the same temperature)
(a) 4
(b) 3
(c) 2
(d) 5

Shahina -

Numerade Educator

Problem 22

Saturated solution of $\mathrm{KNO}_{3}$ is used to make 'salt bridge' because
(a) velocity of $\mathrm{K}^{+}$ is greater than that of $\mathrm{NO}_{3}^{-}$
(b) velocity of $\mathrm{NO}_{3}^{-}$ is greater than that of $\mathrm{K}^{+}$
(c) velocities of both $\mathrm{K}^{+}$ and $\mathrm{NO}_{3}^{-}$ are nearly the same
(d) $\mathrm{KNO}_{3}$ is highly soluble in water

Shahina -

Numerade Educator

Problem 23

The standard reduction potentials of $\mathrm{Pt}\left|\mathrm{Cr}_{2} \mathrm{O}_{2}^{2-}, \mathrm{Cr}^{+3} ; \mathrm{Pt}\right| \mathrm{MnO}_{4}^{-}, \mathrm{Mn}^{+2}$
$\mathrm{Pt} \mid \mathrm{Ce}^{+4}, \mathrm{Ce}^{+3}$ in the presence of acid are
$1.33 \mathrm{~V}, 1.51 \mathrm{~V}$ and $1.61 \mathrm{~V}$, respectively, at $25^{\circ} \mathrm{C}$. The decreasing order of oxidizing power is
(a) $\mathrm{Cr}_{2} \mathrm{O}_{7}^{2-}>\mathrm{MnO}_{4}^{-}>\mathrm{Ce}^{+4}$
(b) $\mathrm{MnO}_{4}^{-}>\mathrm{Cr}_{2} \mathrm{O}_{7}^{2-}>\mathrm{Ce}^{+4}$
(c) $\mathrm{Ce}^{+4}>\mathrm{MnO}_{4}^{-}>\mathrm{Cr}_{2} \mathrm{O}_{7}^{2-}$
(d) $\mathrm{MnO}_{4}^{-}>\mathrm{Ce}^{\mathrm{i4}}>\mathrm{Cr}_{2} \mathrm{O}_{7}^{2-}$

Aadit Sharma

Numerade Educator

Problem 24

The standard reduction potentials at $25^{\circ} \mathrm{C}$ of $\mathrm{Li}^{+}\left|\mathrm{Li}, \mathrm{Ba}^{2+}\right| \mathrm{Ba}, \mathrm{Na}^{+} \mid \mathrm{Na}$ and $\mathrm{Mg}^{2+} \mid \mathrm{Mg}$
are $-3.05,-2.73,-2.71$ and $-2.37 \mathrm{~V}$,
respectively. Which is the strongest reducing agent?
(a) $\mathrm{Li}$
(b) $\mathrm{Ba}$
(c) $\mathrm{Na}$
(d) $\mathrm{Mg}$

Narayan Hari

Numerade Educator

Problem 25

Some standard electrode potentials are given:
$$
\begin{array}{l}
\mathrm{Fe}^{2+}+2 \mathrm{e}^{-} \rightarrow \mathrm{Fe} ; E^{\circ}=-0.440 \mathrm{~V} \\
\mathrm{Fe}^{3+}+3 \mathrm{e}^{-} \rightarrow \mathrm{Fe} ; E^{\circ}=-0.036 \mathrm{~V}
\end{array}
$$
The standard electrode potential for:
$\mathrm{Fe}^{3+}+\mathrm{e}^{-} \rightarrow \mathrm{Fe}^{2+}$, is
(a) $-0.476 \mathrm{~V}$
(b) $-0.404 \mathrm{~V}$
(c) $+0.988 \mathrm{~V}$
(d) $+0.772 \mathrm{~V}$

Mahipal Kumawat

Mahipal Kumawat

Numerade Educator

Problem 26

The dissociation constant for $\mathrm{CH}_{3} \mathrm{COOH}$ is $1.8 \times 10^{-5}$ at $298 \mathrm{~K}$. The electrode potential for the half-cell: $\mathrm{Pt} / \mathrm{H}_{2}$ $(1$ bar $) \mid 0.5 \mathrm{M}-\mathrm{CH}_{3} \mathrm{COOH}$, at $298 \mathrm{~K}$
is $(\log 2=0.3 ; \log 3=0.48 ; 2.303 R T / F$
$=0.06$ )
(a) $-0.3024 \mathrm{~V}$
(b) $-0.1512 \mathrm{~V}$
(c) $+0.3024 \mathrm{~V}$
(d) $+0.1512 \mathrm{~V}$

Himanshu Kushwaha

Himanshu Kushwaha

Numerade Educator

Problem 27

At $25^{\circ} \mathrm{C}$, the solubility product of $\mathrm{CuCl}$ is $2.0 \times 10^{-7}$ and $E_{\mathrm{C}^{-} \mathrm{Cucl} \mathrm{Cu}}^{0}$ is $0.128 \mathrm{~V}$.
The value of $E_{\mathrm{cu}^{*} \mid \mathrm{ca}}^{\circ}$ is $(\log 2=0.3$;
$2.303 R T / F=0.06)$
(a) $-0.274 \mathrm{~V}$
(b) $-0.402 \mathrm{~V}$
(c) $+0.53 \mathrm{~V}$
(d) $+0.402 \mathrm{~V}$

Narayan Hari

Numerade Educator

Problem 28

The standard reduction potential of oxygen in acidic solution is $1.23 \mathrm{~V}\left(\mathrm{O}_{2}\right.$ $\left.+4 \mathrm{H}_{3} \mathrm{O}^{+}+4 \mathrm{e}^{-} \rightarrow 6 \mathrm{H}_{2} \mathrm{O}\right) .$ The standard
reduction potential of oxygen in basic solution is $(2.303 R T / F=0.06)$
(a) $-1.23 \mathrm{~V}$
(b) $-0.39 \mathrm{~V}$
(c) $+0.39 \mathrm{~V}$
(d) $+2.07 \mathrm{~V}$

David Collins

Numerade Educator

Problem 29

The standard potentials of $\mathrm{MnO}_{4}^{-} \mid \mathrm{Mn}^{2+}$ and $\mathrm{MnO}_{2} \mid \mathrm{Mn}^{2+}$ electrodes in acid solution are $1.51$ and $1.23 \mathrm{~V}$, respectively. $\begin{array}{lll}\text { Standard } & \text { electrode } & \text { potential } & \text { for }\end{array}$ the electrode, $\mathrm{MnO}_{4}^{-} \mid \mathrm{MnO}_{2}$ in acid solution is
(a) $+1.697 \mathrm{~V}$
(b) $+5.09 \mathrm{~V}$
(c) $+0.28 \mathrm{~V}$
(d) $+1.37 \mathrm{~V}$

Narayan Hari

Numerade Educator

Problem 30

The following reactions represent the reduction of $\mathrm{IO}_{3}^{-}$ ion into $\mathrm{I}^{-}$ ion in acidic and basic medium. Predict in which medium $\mathrm{IO}_{3}^{-}$ ion will act as a better oxidizing agent? $\mathrm{IO}_{3}^{-}+6 \mathrm{H}^{+}+6 \mathrm{e}^{-} \rightarrow \mathrm{I}^{-}+3 \mathrm{H}_{2} \mathrm{O}$
$E^{\circ}=+0.907 \mathrm{~V}$
$\mathrm{IO}_{3}^{-}+3 \mathrm{H}_{2} \mathrm{O}+6 \mathrm{e}^{-} \rightarrow \mathrm{I}^{-}+6 \mathrm{OH}^{-}$
$E^{\circ}=+0.260 \mathrm{~V}$
(a) Acid medium
(b) Basic medium
(c) Equally in both
(d) Not predictable

Anand Jangid

Numerade Educator

Problem 31

The correct cell diagram for the following reaction and $E^{\circ}$ for the cell is
(a) $(\mathrm{Pt}) \mathrm{H}_{2}\left|\mathrm{H}^{+} \| \mathrm{Br}^{-}\right| \mathrm{AgBr} \mid \mathrm{Br}_{2}(\mathrm{Pt})$
$E^{\circ}=0.10 \mathrm{~V}$
(b) $(\mathrm{Pt}) \mathrm{H}_{2}\left|\mathrm{H}^{+} \| \mathrm{Br}^{-}\right| \mathrm{AgBr} \mid \mathrm{Br}_{2}(\mathrm{Pt})$
$E^{\circ}=-0.10 \mathrm{~V}$
(c) $(\mathrm{Pt}) \mathrm{Br}_{2}|\mathrm{AgBr}| \mathrm{Br}^{-} \| \mathrm{H}^{+} \mid \mathrm{H}_{2}(\mathrm{Pt}) ;$
$E^{\circ}=0.10 \mathrm{~V}$
(d) (Pt) $\mathrm{Br}_{2} \mid$ AgBr $\left|\mathrm{Br}^{-} \| \mathrm{H}^{+}\right| \mathrm{H}_{2}(\mathrm{Pt}) ;$
$E^{\circ}=-0.10 \mathrm{~V}$

Ivan Kochetkov

Numerade Educator

Problem 32

In an experimental set-up for the measurement of EMF of a half-cell using a reference electrode and a salt bridge, when the salt bridge is removed, the voltage
(a) remains the same
(b) increases to maximum
(c) decreases half the value
(d) drops to zero

Shahina -

Numerade Educator

Problem 33

After some time, the voltage of an electrochemical cell becomes zero. This is because
(a) their electrode potential becomes zero.
(b) their reduction potential become equal but have opposite sign.
(c) their reduction potential become equal and have the same sign.
(d) the ions of the electrolyte in the salt bridge stop moving.

Ahmed Ali

Numerade Educator

Problem 34

The cell reaction for the given cell is spontaneous if $\mathrm{Pt}, \mathrm{Cl}_{2}\left(P_{1} \mathrm{~atm}\right)\left|\mathrm{Cl}^{-}\right| \mathrm{Cl}_{2}$
$\left(P_{2} \mathrm{~atm}\right), \mathrm{Pt}$
(a) $P_{1}>P_{2}$
(b) $P_{1}<P_{2}$
(c) $P_{1}=P_{2}$
(d) $P_{1}=1$ atm

Ivan Kochetkov

Numerade Educator

Problem 35

Which one of the following statements is incorrect regarding an electrochemical cell?
(a) The electrode on which oxidation takes place is called anode.
(b) Anode is the negative pole.
(c) The direction of the current is same as that of the direction of flow of electrons.
(d) The flow of current is partly due to flow of electrons and partly due to flow of ions.

Raghvendra Singh

Raghvendra Singh

Numerade Educator

Problem 36

When an electric current is drawn from a galvanic cell
(a) EMF suddenly increases.
(b) EMF gradually increases and attains a maximum value.
(c) EMF decreases and finally falls to zero.
(d) EMF must remain constant.

Shahina -

Numerade Educator

Problem 37

Identification of anode and cathode in an electrochemical cell is made by the use of
(a) Galvanometer
(b) Salt bridge
(c) Voltmeter
(d) Potentiometer

Shahina -

Numerade Educator

Problem 38

For the cell $\mathrm{Zn}\left|\mathrm{Zn}^{2+} \| \mathrm{Cu}^{2+}\right| \mathrm{Cu}$, if the
concentration of both, $\mathrm{Zn}^{2+}$ and $\mathrm{Cu}^{2+}$ ions are doubled, the EMF of the cell
(a) doubles
(b) reduces to half
(c) remains same
(d) becomes zero

Satpal Satpal

Numerade Educator

Problem 39

The standard EMF of a galvanic cell can be calculated from
(a) the size of the electrode
(b) the $\mathrm{pH}$ of the solution
(c) the amount of metal in the anode
(d) the $E^{\circ}$ values of the half-cells

Shahina -

Numerade Educator

Problem 40

The value of equilibrium constant for a feasible cell reaction must be
(a) $\leq 1$
(b) Zero
$(\mathrm{c})=1$
(d) $>1$

Shahina -

Numerade Educator

Problem 41

If the cell reaction is spontaneous then
(a) $\Delta G^{\circ}=-\mathrm{ve}$
(b) $E_{\text {red }}^{\circ}=-$ ve
(c) $E_{\text {red }}^{\circ}=+$ ve
(d) $\Delta G=-$ ve

Shahina -

Numerade Educator

Problem 42

Which of the following pair of metals, when coupled, will give maximum EMF for a voltaic cell?
(a) Fe and $\mathrm{Cu}$
(b) $\mathrm{Pb}$ and $\mathrm{Au}$
(c) $\mathrm{Cu}$ and $\mathrm{Au}$
(d) $\mathrm{Ca}$ and $\mathrm{Cu}$

Shahina -

Numerade Educator

Problem 43

When a lead storage battery is charged
(a) $\mathrm{PbO}_{2}$ dissolves.
(b) the lead electrode becomes coated with lead sulphate.
(c) sulphuric acid is regenerated.
(d) the amount of acid decreases.

Shahina -

Numerade Educator

Problem 44

Use of lithium metal as an electrode in high energy density batteries is due to
(a) lithium is the lightest element.
(b) lithium has the highest oxidation potential.
(c) lithium is quite reactive.
(d) lithium does not corrode readily.

Shahina -

Numerade Educator

Problem 45

A depolarizer used in dry cell batteries is
(a) $\mathrm{NH}_{4} \mathrm{Cl}$
(b) $\mathrm{MnO}_{2}$
(c) $\mathrm{KOH}$
(d) $\mathrm{Na}_{3} \mathrm{PO}_{4}$

Shahina -

Numerade Educator

Problem 46

Which is correct about fuel cells?
(a) Cell continuously run as long as fuels are supplied.
(b) These are more efficient and free from pollution.
(c) These are used to provide power and drinking water to astronauts in space programme.
(d) All of these

Shahina -

Numerade Educator

Problem 47

When a lead storage battery is discharged
(a) $\mathrm{SO}_{2}$ is evolved
(b) lead sulphate is consumed
(c) lead is formed
(d) sulphuric acid is consumed

Shahina -

Numerade Educator

Problem 48

For a cell reaction involving a twoelectron change, the standard EMF of the cell is found to be $0.295 \mathrm{~V}$ at $25^{\circ} \mathrm{C}$. The equilibrium constant of the reaction at $25^{\circ} \mathrm{C}$ will be
(a) $1 \times 10^{10}$
(b) $1 \times 10^{-10}$
(c) $29.5 \times 10^{-2}$
(d) $2 \times 10^{10}$

Satpal Satpal

Numerade Educator

Problem 49

The $E_{\text {Cell }}$ for $\mathrm{Ag}(\mathrm{s}) \mid$ AgI (satd) $\| \mathrm{Ag}^{+}$ $(0.10 \mathrm{M}) \mid \mathrm{Ag}(\mathrm{s})$ is $+0.413 \mathrm{~V}$. What is the
value of $K_{s p}$ of $\mathrm{Ag}$ I?
(a) $1.0 \times 10^{-8}$
(b) $1.0 \times 10^{-7}$
(c) $1.0 \times 10^{-14}$
(d) $1.0 \times 10^{-16}$

David Collins

Numerade Educator

Problem 50

Assuming that hydrogen behaves as an ideal gas, what is the EMF of the cell at $25^{\circ} \mathrm{C}$ if $P_{1}=600 \mathrm{~mm}$ and $P_{2}=420 \mathrm{~mm}$ :
$\mathrm{Pt}\left|\mathrm{H}_{2}\left(P_{1}\right)\right| \mathrm{HCl}\left|\mathrm{H}_{2}\left(P_{2}\right)\right| \mathrm{Pt} ?$ [Given:
$2.303 R T / F=0.06, \log 7=0.85]$
(a) $-0.0045 \mathrm{~V}$
(b) $-0.0 \mathrm{~V}$
(c) $+0.0045 \mathrm{~V}$
(d) $+0.0015 \mathrm{~V}$

Hunza Gilgit

Numerade Educator

Problem 51

For the electrochemical cell, $\mathrm{M} \mid \mathrm{M}^{+}$ $\mathrm{X}^{-} \mid \mathrm{X}, E_{\mathrm{M}^{+} \mathrm{M}}^{\circ}=0.44 \mathrm{~V}$ and $E_{\mathrm{X} \mid \mathrm{X}^{-}}^{\circ}=0.33$
From this data, one can deduce that
(a) $\mathrm{M}+\mathrm{X} \rightarrow \mathrm{M}^{+}+\mathrm{X}^{-}$ is the spontaneo
reaction

Himanshu Kushwaha

Himanshu Kushwaha

Numerade Educator

Problem 52

The EMF of the cell: $\mathrm{Zn} \mid \mathrm{Zn}^{2+}(0.01 \mathrm{M}) \|$
$\mathrm{Fe}^{2+}(0.001 \mathrm{M}) \mid \mathrm{Fe}$ at $298 \mathrm{~K}$ is $0.2905 \mathrm{~V}$
then the value of equilibrium constant for the cell reaction is
(a) $\begin{array}{ll}e^{\frac{0.32}{0.0295}} & \text { (b) } 10^{\frac{0.32}{0.0295}}\end{array}$
(c) $10^{\frac{0.26}{0.0295}} \quad$ (d)
$10^{\frac{0.52}{0.0591}}$

Himanshu Kushwaha

Himanshu Kushwaha

Numerade Educator

Problem 54

The standard EMF for the cell reaction:
$\mathrm{Zn}(\mathrm{s})+\mathrm{Cu}^{2+}(\mathrm{aq}) \rightarrow \mathrm{Zn}^{2+}(\mathrm{aq})+\mathrm{Cu}(\mathrm{s})$ is
$1.10$ volts at $25^{\circ} \mathrm{C}$. The EMF of the cell reaction when $0.1 \mathrm{M} \mathrm{Cu}^{2+}$ and $0.1 \mathrm{M} \mathrm{Zn}^{2+}$
solutions are used at $25^{\circ} \mathrm{C}$ is
(a) $1.10 \mathrm{~V}$
(b) $1.041 \mathrm{~V}$
(c) $-1.10 \mathrm{~V}$
(d) $-1.041 \mathrm{~V}$

Hast Aggarwal

Numerade Educator

Problem 55

For the cell: $\mathrm{Ni}\left|\mathrm{Ni}^{2+} \| \mathrm{Cu}^{2+}\right| \mathrm{Cu}$;
$E^{\circ}=0.77 \mathrm{~V} .$ By which of the following activity, $E_{\text {cell }}$ will increase?
(a) On decreasing $\left[\mathrm{Ni}^{+2}\right]$
(b) On decreasing [Cu $^{+2}$ ]
(c) On increasing mass of $\mathrm{Ni}$ electrode
(d) On increasing mass of Cu electrode

Satpal Satpal

Numerade Educator

Problem 56

The standard EMF of a Daniel cell at 298 $\mathrm{K}$ is $E_{1} .$ When the concentration of $\mathrm{ZnSO}_{4}$ is $1.0 \mathrm{M}$ and that of $\mathrm{CuSO}_{4}$ is $0.01 \mathrm{M}$, the EMF becomes $E_{2}$ at $298 \mathrm{~K}$. The correct relationship between $E_{1}$ and $E_{2}$ is
(a) $E_{1}=E_{2}$
(b) $E_{2}=0$
(c) $E_{1}>E_{2}$
(d) $E_{1}<E_{2}$

Mishal Gul

Numerade Educator

Problem 57

For a reaction $\mathrm{A}(\mathrm{s})+2 \mathrm{~B}^{+} \rightarrow \mathrm{A}^{2+}+\mathrm{B}(\mathrm{s}) ; K_{\mathrm{C}}$
has been found to be $10^{12}$. The EMF of the cell is
(a) $0.354 \mathrm{~V}$
(b) $0.708 \mathrm{~V}$
(c) $0.534 \mathrm{~V}$
(d) $0.453 \mathrm{~V}$

Dr. Satish Ingale

Dr. Satish Ingale

Numerade Educator

Problem 58

An electrochemical cell is set up as follows:
$\mathrm{Pt}\left|\mathrm{H}_{2}(\mathrm{~s})(1 \mathrm{~atm})\right| 0.001 \mathrm{M} \mathrm{HCl} \|$
$0.1 \mathrm{M} \overrightarrow{\mathrm{HA}}\left|\mathrm{H}_{2}(\mathrm{~s})(1 \mathrm{~atm})\right| \mathrm{Pt}$
EMF of this cell is zero because (p $K_{a}$ of $\mathrm{HA}=5$ )
(a) molar concentrations of acids are different
(b) Temperature is constant
(c) $\mathrm{pH}$ of two solutions are same
(d) both are standard hydrogen electrodes

Satpal Satpal

Numerade Educator

Problem 59

The reaction: $\mathrm{H}_{2}(\mathrm{~g})+2 \mathrm{AgCl}(\mathrm{s})$
$\rightarrow 2 \mathrm{H}^{+}(\mathrm{aq})+2 \mathrm{Cl}^{-}(\mathrm{aq})+2 \mathrm{Ag}(\mathrm{s})$ occurs in
the galvanic cell
(a) $\mathrm{Ag}|\mathrm{AgCl}(\mathrm{s})| \mathrm{KCl}(\mathrm{aq})\left|\mathrm{AgNO}_{3}(\mathrm{aq})\right|$
$\mathrm{Ag}$
(b) $\mathrm{Pt}\left|\mathrm{H}_{2}(\mathrm{~g})\right| \mathrm{HCl}(\mathrm{aq})\left|\mathrm{AgNO}_{3}(\mathrm{aq})\right| \mathrm{Ag}$
(c) $\mathrm{Pt}\left|\mathrm{H}_{2}(\mathrm{~g})\right| \mathrm{HCl}(\mathrm{aq})|\mathrm{AgCl}(\mathrm{s})| \mathrm{Ag}$
(d) $\mathrm{Pt}\left|\mathrm{H}_{2}(\mathrm{~g})\right| \mathrm{KCl}(\mathrm{aq})|\mathrm{AgCl}(\mathrm{s})| \mathrm{Ag}$

Narayan Hari

Numerade Educator

Problem 60

The standard reduction potentials in acidic conditions are $0.77 \mathrm{~V}$ and $0.53 \mathrm{~V}$, respectively, for $\mathrm{Fe}^{3+} \mid \mathrm{Fe}^{2+}$ and $\mathrm{I}_{3}^{-} \mid \mathrm{I}^{-}$
couples. The equilibrium constant for the reaction: $2 \mathrm{Fe}^{3+}+3 \mathrm{I}^{-} \rightleftharpoons 2 \mathrm{Fe}^{2+}+\mathrm{I}_{3}^{-}$, is
$(2.303 R T / F=0.06)$
(a) $2 \times 10^{8}$
(b) $10^{8}$
(c) $10^{4}$
(d) $10^{-8}$

Narayan Hari

Numerade Educator

Problem 61

The following electrochemical cell has been set up: $\mathrm{Pt}(\mathrm{s}) \mid \mathrm{Fe}^{3+}, \mathrm{Fe}^{2+}(\mathrm{a}=1) \| \mathrm{Ce}^{4+}$
$\mathrm{Ce}^{3+}(\mathrm{a}=1) \mid \mathrm{Pt}(\mathrm{s}) ; E^{\circ}\left(\mathrm{Fe}^{3+} \mid \mathrm{Fe}^{2+}\right)=0.77 \mathrm{~V}$
$E^{\circ}\left(\mathrm{Ce}^{4} \mid \mathrm{Ce}^{3+}\right)=1.61 \mathrm{~V} .$ If an ammeter
is connected between the two platinum electrodes, predict the direction of flow of current. Will the current increase on decrease with time?
(a) Ce electrode to $\mathrm{Fe}$ electrode, decrease
(b) $\mathrm{Ce}$ electrode to $\mathrm{Fe}$ electrode, increase
(c) $\mathrm{Fe}$ electrode to $\mathrm{Ce}$ electrode, decrease
(d) Fe electrode to $\mathrm{Ce}$ electrode, increase

Narayan Hari

Numerade Educator

Problem 62

For the reaction: $\mathrm{H}_{2}(1$ bar $)+2 \mathrm{AgCl}(\mathrm{s})$ $\rightleftharpoons 2 \mathrm{Ag}(\mathrm{s})+2 \mathrm{H}^{+}(0.1 \mathrm{M})+2 \mathrm{Cl}^{-}(0.1 \mathrm{M})$
$\Delta G^{0}=-48,250 \mathrm{~J}$ at $25^{\circ} \mathrm{C}$. The EMF of cell
in which the given reaction takes place is
(a) $0.25 \mathrm{~V}$
(b) $0.37 \mathrm{~V}$
(c) $0.13 \mathrm{~V}$
(d) $0.0 .49 \mathrm{~V}$

Rajesh Singh

Numerade Educator

Problem 63

A cell contains two hydrogen electrodes. The negative electrode is in contact with a solution of $10^{-6} \mathrm{M}$ hydrogen ions. The EMF of the cell is $0.118 \mathrm{~V}$ at $25^{\circ} \mathrm{C}$. The concentration of hydrogen ions at the positive electrode is
(a) $10^{-6} \mathrm{M}$
(b) $10^{-3} \mathrm{M}$
(c) $10^{-4} \mathrm{M}$
(d) $10^{-5} \mathrm{M}$

Aadit Sharma

Numerade Educator

Problem 64

The standard potentials of $\mathrm{OCl}^{-} / \mathrm{Cl}^{-}$ and $\mathrm{Cl}^{-} / \mathrm{Cl}_{2}$ are $0.94 \mathrm{~V}$ and $-1.36 \mathrm{~V}$, respectively.
The $E^{\circ}$ value of $\mathrm{OCl}^{-} / \mathrm{Cl}_{2}$ will be
(a) $3.24 \mathrm{~V}$
(b) $-0.42 \mathrm{~V}$
(c) $-2.30 \mathrm{~V}$
(d) $0.52 \mathrm{~V}$

Himanshu Kushwaha

Himanshu Kushwaha

Numerade Educator

Problem 65

From the following $E^{\circ}$ values for the half-cells:
(i) $\mathrm{D} \rightarrow \mathrm{D}^{2+}+2 \mathrm{e}^{-} ; E^{\circ}=-1.5 \mathrm{~V}$
(ii) $\mathrm{B}^{+}+\mathrm{e}^{-} \rightarrow \mathrm{B} ; E^{\circ}=-0.5 \mathrm{~V}$
(iii) $\mathrm{A}^{3-} \rightarrow \mathrm{A}^{2-}+\mathrm{e}^{-} ; E^{\circ}=1.5 \mathrm{~V}$
(iv) $\mathrm{C}^{2+}+\mathrm{e}^{-} \rightarrow \mathrm{C}^{+} ; E^{\circ}=+0.5 \mathrm{~V}$
Which combination of two half-cells would result in a cell with largest potential?
(a) $\mathrm{i}$ and iii
(b) $\mathrm{i}$ and iv
(c) iii and iv
(d) ii and iv

Narayan Hari

Numerade Educator

Problem 66

Which of the following statements does not differentiate between electrochemical cell and electrolytic cell?
(a) Spontaneous or non-spontaneous nature of the chemical process.
(b) Chemical reactions occurring at the electrodes
(c) Positive and negative nature of anode.

Shahina -

Numerade Educator

Problem 67

The electrode through which electrons enter the electrolytic solution is
(a) cathode
(b) anode
(c) may be anode or cathode
(d) both, anode and cathode

Shahina -

Numerade Educator

Problem 68

Which process occurs in the electrolysis of an aqueous solution of nickel chloride at nickel anode?
(a) $\mathrm{Ni} \rightarrow \mathrm{Ni}^{2+}+2 \mathrm{e}^{-}$
(b) $\mathrm{Ni}^{2+}+2 \mathrm{e}^{-} \rightarrow \mathrm{Ni}$
(c) $2 \mathrm{Cl}^{-} \rightarrow \mathrm{Cl}_{2}+2 \mathrm{e}^{-}$
(d) $2 \mathrm{H}^{+}+2 \mathrm{e}^{-} \rightarrow \mathrm{H}_{2}$

Shahina -

Numerade Educator

Problem 69

If mercury is used as a cathode during the electrolysis of an aqueous $\mathrm{NaCl}$ solution, the ions discharged at cathode are
(a) $\mathrm{H}^{+}$
(b) $\mathrm{Na}^{+}$
(c) $\mathrm{OH}^{-}$
(d) $\mathrm{Cl}^{-}$

Shahina -

Numerade Educator

Problem 70

Electrochemical equivalent is more for
(a) Hydrogen
(b) Silver
(c) Copper
(d) Zinc

Shahina -

Numerade Educator

Problem 71

The electrolytic bath used in gold plating of copper articles contains
(a) Molten gold
(b) Copper sulphate(aq)
(c) $\mathrm{AuCl}_{3}(\mathrm{aq})$
(d) $\mathrm{AuCl}_{3}+\mathrm{NaCN}(\mathrm{aq})$

Shahina -

Numerade Educator

Problem 72

Copper can be deposited from acidified copper sulphate and alkaline cuprous cyanide. If the same current is passed for a definite time
(a) the amount of copper deposited from acidic copper sulphate will be higher
(b) the amount of copper deposited from alkaline cuprous cyanide will be higher
(c) the same amount of copper will be deposited
(d) copper will not deposit in either case

Alkendra Singh

Numerade Educator

Problem 73

In the electrolytic cell, flow of electrons is from
(a) Cathode to anode in solution
(b) Cathode to anode through external supply
(c) Cathode to anode through internal supply
(d) Anode to cathode through internal supply

Shahina -

Numerade Educator

Problem 74

Electrolytic cell is used to convert
(a) Chemical energy to electrical energy
(b) Electrical energy to chemical energy
(c) Chemical energy to mechanical energy
(d) Electrical energy to mechanical energy

Shahina -

Numerade Educator

Problem 75

Faraday's law of electrolysis fails when
(a) temperature is increased
(b) inert electrodes are used
(c) a mixture of electrolytes is used
(d) in none of these cases

Shahina -

Numerade Educator

Problem 76

Using same quantity of current, which among $\mathrm{Na}, \mathrm{Mg}$ and $\mathrm{Al}$ is deposited more (by mass) during electrolysis of their molten salts?
(a) $\mathrm{Na}$
(b) $\mathrm{Mg}$
(c) $\mathrm{Al}$
(d) All in same

Shahina -

Numerade Educator

Problem 77

A certain current liberated $0.50 \mathrm{~g}$ of hydrogen in $2 \mathrm{~h}$. How many grams of copper can be liberated by the same current flowing for the same time in a copper sulphate solution? $(\mathrm{Cu}=63.5)$
(a) $12.7 \mathrm{~g}$
(b) $15.88 \mathrm{~g}$
(c) $31.75 \mathrm{~g}$
(d) $63.5 \mathrm{~g}$

Shahina -

Numerade Educator

Problem 78

A current of $3.7 \mathrm{~A}$ is passed for $6 \mathrm{~h}$ between nickel electrodes in $0.50$ l of $2 \mathrm{M}$ solution of $\mathrm{Ni}\left(\mathrm{NO}_{3}\right)_{2} .$ The molarity of $\mathrm{Ni}^{2+}$ at the end of electrolysis is
(a) $1.172 \mathrm{M}$
(b) $0.172 \mathrm{M}$
(c) $0.586 \mathrm{M}$
(d) $2 \mathrm{M}$

Shahina -

Numerade Educator

Problem 79

The current efficiency of an electrodeposition of copper metal in which $9.8 \mathrm{~g}$ of copper is deposited by a current of 3 A for $10000 \mathrm{~s}$, from aqueous copper sulphate solution, is about
(a) $60 \%$
(b) $99 \%$
(c) $92 \%$
(d) $75 \%$

Nicole Smina

Numerade Educator

Problem 80

On passing electricity through dilute $\mathrm{H}_{2} \mathrm{SO}_{4}$ solution, the mass of substances liberated at the cathode and anode are in the ratio of
(a) $1: 8$
(b) $8: 1$
(c) $1: 32$
(d) $1: 16$

Mishal Gul

Numerade Educator

Problem 81

The electrochemical equivalents of two substances are $E_{1}$ and $E_{2}$. The current that must pass to deposit the same amount at the cathodes in the same time must be in the ratio of
(a) $E_{1}: E_{2}$
(b) $E_{2}: E_{1}$
(c) $\left(E_{1}-E_{2}\right): E_{2}$
(d) $E_{1}:\left(E_{2}-E_{1}\right)$

Shahina -

Numerade Educator

Problem 82

The same quantity of electricity is passed through one molar solution of $\mathrm{H}_{2} \mathrm{SO}_{4}$ and one molar solution of $\mathrm{HCl}$. The amount of hydrogen evolved from $\mathrm{H}_{2} \mathrm{SO}_{4}$ as compared to that from $\mathrm{HCl}$ is
(a) the same
(b) twice as such
(c) one half as such
(d) dependent on size of electrode

Satpal Satpal

Numerade Educator

Problem 83

In the electrolysis of acidified $\mathrm{AgNO}_{3}$ solution using Pt-electrodes, the anode reaction is
(a) $2 \mathrm{NO}_{3}^{-} \rightarrow 2 \mathrm{NO}_{2}+\mathrm{O}_{2}+2 \mathrm{e}^{-}$
(b) $\mathrm{NO}_{3}^{-} \rightarrow \mathrm{NO}+\frac{1}{2} \mathrm{O}_{2}+\mathrm{e}^{-}$
(c) $2 \mathrm{H}_{2} \mathrm{O} \rightarrow 4 \mathrm{H}^{+}+\mathrm{O}_{2}+4 \mathrm{e}^{-}$
(d) $\mathrm{Pt} \rightarrow \mathrm{Pt}^{3+}+3 \mathrm{e}^{-}$

Shalini Tyagi

Numerade Educator

Problem 84

Two platinum electrodes were immersed in a solution of $\mathrm{CuSO}_{4}$ and electric current was passed through the solution. After some time, it was found that colour of $\mathrm{CuSO}_{4}$ disappeared with the evolution of gas at the electrode. The colourless solution contains
(a) platinum sulphate
(b) copper sulphate
(c) copper hydroxide
(d) sulphuric acid

Shahina -

Numerade Educator

Problem 85

A solution containing $1.0 \mathrm{M}$ each of $\mathrm{Cu}\left(\mathrm{NO}_{3}\right)_{2}, \mathrm{Mg}\left(\mathrm{NO}_{3}\right)_{2}, \mathrm{AgNO}_{3}, \mathrm{Hg}\left(\mathrm{NO}_{3}\right)_{2}$
is being electrolysed using inert electrodes. The values of standard electrode potential are: $\mathrm{Ag}^{+}\left|\mathrm{Ag}=0.80 \mathrm{~V}, \mathrm{Hg}^{2+}\right| \mathrm{Hg}=0.79 \mathrm{~V}$
$\mathrm{Cu}^{2+}\left|\mathrm{Cu}=0.34 \mathrm{~V}, \mathrm{Mg}^{2+}\right| \mathrm{Mg}=-2.37 \mathrm{~V}$
With increasing voltage, the sequence of deposit of metals on the cathode will be
(a) $\mathrm{Ag}, \mathrm{Hg}, \mathrm{Cu}, \mathrm{Mg}$
(b) $\mathrm{Mg}, \mathrm{Cu}, \mathrm{Hg}, \mathrm{Ag}$
(c) $\mathrm{Ag}, \mathrm{Mg}, \mathrm{Cu}$
(d) $\mathrm{Cu}, \mathrm{Hg}, \mathrm{Ag}$

Shahina -

Numerade Educator

Problem 86

During the electrolysis of an aqueous salt solution, the $\mathrm{pH}$ in the space near one of the electrode was increased and the other one was decreased. The salt solution was
(a) $\mathrm{NaCl}$ (very dilute)
(b) $\mathrm{ZnCl}_{2}$
(c) $\mathrm{NaCl}$ (Conc.)

Shahina -

Numerade Educator

Problem 87

Two electrolytic cells, one containing acidified ferrous chloride and another acidified ferric chloride, are connected in
series. The mass ratio of iron deposited at cathodes in the two cells will be
(a) $3: 1$
(b) $2: 3$
(c) $1: 1$
(d) $3: 2$

Shahina -

Numerade Educator

Problem 88

A galvanic cell is set up from a zinc bar weighing $100 \mathrm{~g}$ and $1.0 \mathrm{~L}$ of $1.0 \mathrm{M}$ copper sulphate solution. How long would the cell run if it is assumed to deliver a steady current of $1.0 \mathrm{~A} ?(\mathrm{Zn}=65.4)$
(a) $53.6 \mathrm{~h}$
(b) $26.8 \mathrm{~h}$
(c) $81.97 \mathrm{~h}$
(d) $40.99 \mathrm{~h}$

Bhumika Jayee

Numerade Educator

Problem 89

An ion is a reduced to the element when it absorbs $6 \times 10^{20}$ electrons. The number of equivalents of the ion is
(a) $0.10$
(b) $0.01$
(c) $0.001$
(d) $0.0001$

Shahina -

Numerade Educator

Problem 90

In the lead storage battery, the anode reaction is $\mathrm{Pb}(\mathrm{s})+\mathrm{HSO}_{4}^{-}+\mathrm{H}_{2} \mathrm{O}$
$\rightarrow \mathrm{PbSO}_{4}(\mathrm{~s})+\mathrm{H}_{3} \mathrm{O}^{+}+2 \mathrm{e}^{-} .$ How many
grams of $\mathrm{Pb}$ will be used up to deliver $1 \mathrm{~A}$ for $100 \mathrm{~h}$ ? $(\mathrm{Pb}=208)$
(a) $776 \mathrm{~g}$
(b) $388 \mathrm{~g}$
(c) $194 \mathrm{~g}$
(d) $0.1 \mathrm{~g}$

David Collins

Numerade Educator

Problem 91

The copper anode of a cell containing silver nitrate solution weighs $60.0 \mathrm{~g}$. After passing current for some time, it is found that $3.24 \mathrm{~g}$ of silver if deposited on the platinum cathode. What is the final weight of the anode? $(\mathrm{Ag}=108, \mathrm{Cu}=64)$
(a) $0.96 \mathrm{~g}$
(b) $60 \mathrm{~g}$
(c) $59.04 \mathrm{~g}$
(d) $60.96 \mathrm{~g}$

Shalini Tyagi

Numerade Educator

Problem 92

The quantity of electricity required for the reduction of 1 mole of $\mathrm{Fe}_{2} \mathrm{O}_{3}$ to $\mathrm{Fe}$ is
(a) $1 \mathrm{~F}$
(b) $0.33 \mathrm{~F}$

Nikhil Choudhary

Nikhil Choudhary

Numerade Educator

Problem 93

Three faradays of electricity is passed through molten $\mathrm{Al}_{2} \mathrm{O}_{3}$, aqueous solutions of $\mathrm{CuSO}_{4}$ and molten $\mathrm{NaCl}$. The amounts of $\mathrm{Al}, \mathrm{Cu}$ and $\mathrm{Na}$ deposited at the cathodes will be in the molar ratio of
(a) $1: 2: 3$
(b) $3: 2: 1$
(c) $1: 1.5: 3$
(d) $6: 3: 2$

Himanshu Kushwaha

Himanshu Kushwaha

Numerade Educator

Problem 94

Electrolysis of a solution of $\mathrm{HSO}_{4}^{-}$ ions produces $\mathrm{S}_{2} \mathrm{O}_{8}{ }^{2-}$. Assuming $75 \%$ current efficiency, what current should be employed to achieve a production rate of 1 mole of $\mathrm{S}_{2} \mathrm{O}_{8}^{2-}$ per hour?
(a) $71.5 \mathrm{~A}$
(b) $35.7 \mathrm{~A}$
(c) $53.0 \mathrm{~A}$
(d) $143 \mathrm{~A}$

Lottie Adams

Numerade Educator

Problem 95

The number of Faradays required to produce 1 g-atom of $\mathrm{Mg}$ from $\mathrm{MgCl}_{2}$ is
(a) $\overline{1}$
(b) 2
(c) $0.5$
(d) 4

Shahina -

Numerade Educator

Problem 96

Passage of 96,500 coulomb of electricity liberates $\mathrm{L}$ of $\mathrm{O}_{2}$ at $273^{\circ} \mathrm{C}$ and 2 atm during electrolysis.
(a) $5.6$
(b) $16.8$
(c) $22.4$
(d) $11.2$

Shahina -

Numerade Educator

Problem 97

An electrolytic cell contains a solution of $\mathrm{Ag}_{2} \mathrm{SO}_{4}$ and platinum electrodes. $\mathrm{A}$ current is passed until $1.6 \mathrm{~g}$ of $\mathrm{O}_{2}$ has been liberated at anode. The amount of silver deposited at cathode would be
(a) $108.0 \mathrm{~g}$
(b) $1.6 \mathrm{~g}$

Shahina -

Numerade Educator

Problem 98

When 12,000 coulombs of electricity is passed through the electrolyte, $3.0 \mathrm{~g}$ of a metal of atomic mass $96.5 \mathrm{~g} / \mathrm{mol}$ is deposited. The electro-valency of the metal cation in the electrolyte is
(a) $+4$
(b) $+3$
(c) $+2$
(d) $-4$

Himanshu Kushwaha

Himanshu Kushwaha

Numerade Educator

Problem 99

How many electrons flow when a current of $5 \mathrm{~A}$ is passed through a solution for $200 \mathrm{~s}$ ?
(a) $6.022 \times 10^{23}$
(b) $6.24 \times 10^{21}$
(c) $6.024 \times 10^{21}$
(d) $6.022 \times 10^{20}$

Shahina -

Numerade Educator

Problem 100

The current of $9.65$ A flowing for $10 \mathrm{~min}$ deposits $3.0 \mathrm{~g}$ of a metal. The equivalent weight of the metal is
(a) 10
(b) 30
(c) 50
(d) $96.5$

Shahina -

Numerade Educator

Problem 101

If a current of $1.0 \mathrm{~A}$ is drawn from the Daniel cell for $96.5 \mathrm{~min}$, the cathode will gain in weight by $(\mathrm{Cu}=63.5, \mathrm{Zn}=65.4)$
(a) $1.905 \mathrm{~g}$
(b) $1.962 \mathrm{~g}$
(c) $3.81 \mathrm{~g}$
(d) $3.924 \mathrm{~g}$

Satpal Satpal

Numerade Educator

Problem 102

The current required to produce oxygen at the rate of $2.8 \mathrm{ml}$ per second during electrolysis of acidulated water is
(a) $48.25 \mathrm{~A} / \mathrm{s}$
(b) $24.12 \mathrm{~A} / \mathrm{s}$
(c) $96.5 \mathrm{~A} / \mathrm{s}$
(d) $0.0048 \mathrm{~A} / \mathrm{s}$

Shahina -

Numerade Educator

Problem 103

Sodium amalgam is prepared by electrolysis of aqueous $\mathrm{NaCl}$ using $10 \mathrm{~g}$ mercury as cathode. How many Faraday of electricity is required to prepare $18.7 \%$ Na-amalgam, by weight, with a current efficiency of $50 \% ?$
(a) $0.1 \mathrm{~F}$
(b) $0.2 \mathrm{~F}$
(c) $0.05 \mathrm{~F}$
(d) $0.16 \mathrm{~F}$

Narayan Hari

Numerade Educator

Problem 104

Element $\mathrm{A}$ (atomic mass $=112$ ) and element $\mathrm{B}$ (atomic mass $=27$ ) form chlorides. Solutions of these chlorides are electrolysed separately and it is found that when the same quantity of electricity is passed, $5.6 \mathrm{~g}$ of $\mathrm{A}$ was deposited while only $0.9 \mathrm{~g}$ of $\mathrm{B}$ was deposited. The valency of $\mathrm{B}$ is 3 . The valency of $\mathrm{A}$ is
(a) 1
(b) 2
(c) 3
(d) 4

Alkendra Singh

Numerade Educator

Problem 105

The same current was passed successively through solution of zinc-ammonium sulphate and nickel-ammonium sulphate rendered alkaline with ammonia. The weights of zinc and nickel deposited in a certain time were found to be $22.89 \mathrm{~g}$ and $20.55 \mathrm{~g}$, respectively. Given that the chemical equivalent weight of zinc is $32.7$, what is the chemical equivalent weight of nickel?
(a) $58.71$
(b) $29.36$
(c) $14.39$
(d) $36.42$

Dr. Satish Ingale

Dr. Satish Ingale

Numerade Educator

Problem 106

Which of the following solutions have highest resistance?
(a) $1 \mathrm{~N}-\mathrm{NaCl}$
(b) $0.05 \mathrm{~N}-\mathrm{NaCl}$
(c) $2 \mathrm{~N}-\mathrm{NaCl}$
(d) $0.1 \mathrm{~N}-\mathrm{NaCl}$

David Collins

Numerade Educator

Problem 107

Variation of molar conductance of an electrolytic solution with temperature is that it
(a) increases with increase of temperature
(b) decreases with increase of temperature
(c) first increases then decreases
(d) is not affected by temperature

Shahina -

Numerade Educator

Problem 108

Which pure substance will not conduct electricity?
(a) Molten $\mathrm{NaCl}$
(b) Molten KOH

Tanvi Garg

Numerade Educator

Problem 109

The correct order of molar conductance at infinite dilution of $\mathrm{LiCl}, \mathrm{NaCl}$ and $\mathrm{KCl}$ is
(a) $\mathrm{LiCl}>\mathrm{NaCl}>\mathrm{KCl}$
(b) $\mathrm{KCl}>\mathrm{NaCl}>\mathrm{LiCl}$
(c) $\mathrm{NaCl}>\mathrm{KCl}>\mathrm{LiCl}$
(d) $\mathrm{LiCl}>\mathrm{KCl}>\mathrm{NaCl}$

Dr. Satish Ingale

Dr. Satish Ingale

Numerade Educator

Problem 110

The molar conductance of a strong electrolyte at infinite dilution
(a) tends to a finite value, which is above that at higher concentration
(b) tends to a finite value, which is below that at higher concentration
(c) tends to zero
(d) tends to a finite value, which is equal

Shahina -

Numerade Educator

Problem 111

The best conductor of electricity is a $0.1 \mathrm{M}$ solution of
(a) Boric acid
(b) Sulphuric acid
(c) Acetic acid
(d) Propanoic acid

Dr. Satish Ingale

Dr. Satish Ingale

Numerade Educator

Problem 112

The specific conductance of $\mathrm{AgCl}$ solution in water was determined to be $1.8 \times 10^{-6} \Omega^{-1} \mathrm{~cm}^{-1}$ at $298 \mathrm{~K}$. The molar
conductances at infinite dilution, of $\mathrm{Ag}^{+}$ and $\mathrm{Cl}^{-}$ are $67.9$ and $82.1 \Omega^{-1} \mathrm{~cm}^{2} \mathrm{~mol}^{-1}$,
respectively. What is the solubility of AgCl in water?
(a) $1.2 \times 10^{-8} \mathrm{M}$
(b) $1.44 \times 10^{-10} \mathrm{M}$
(c) $1.2 \times 10^{-5} \mathrm{M}$
(d) $1.44 \times 10^{-16} \mathrm{M}$

Akhil Choudhary

Akhil Choudhary

Numerade Educator

Problem 113

Equivalence conductance at infinite dilution of $\mathrm{NH}_{4} \mathrm{Cl}, \mathrm{NaOH}$ and $\mathrm{NaCl}$
are 129.8, $217.4$ and $108.9 \Omega^{-1} \mathrm{~cm}^{2}$
$\mathrm{mol}^{-1}$, respectively. If the equivalent conductance of $0.01 \mathrm{~N}$ solution of $\mathrm{NH}_{4} \mathrm{OH}$ is $9.532 \Omega^{-1} \mathrm{~cm}^{2} \mathrm{~mol}^{-1}$, then the
degree of dissociation of $\mathrm{NH}_{4} \mathrm{OH}$ at this temperature is
(a) $0.04 \%$
(b) $2.1 \%$
(c) $4.0 \%$
(d) $44.7 \%$

Hast Aggarwal

Numerade Educator

Problem 114

The resistance of $1 \mathrm{M}-\mathrm{CH}_{3} \mathrm{COOH}$
solution is $250 \Omega$, when measured in a cell of cell constant $125 \mathrm{~m}^{-1}$. The molar conductivity, in $\Omega^{-1} \mathrm{~m}^{2} \mathrm{~mol}^{-1}$ is
(a) $5.0 \times 10^{-4}$
(b) 500
(c) $2 \times 10^{-3}$
(d) 200

Shalini Tyagi

Numerade Educator

Problem 115

How does the electrical conductivity of $20 \mathrm{ml}$ of $0.2 \mathrm{M}-\mathrm{MgSO}_{4}$ change when
$0.5 \mathrm{M}-\mathrm{Ba}(\mathrm{OH})_{2}$ solution is gradually
added in it, to excess?
(a) decreases continuously
(b) increases continuously
(c) increases and then decreases
(d) decreases am

Varsha Aggarwal

Varsha Aggarwal

Numerade Educator

Problem 116

The equivalent conductivity (in $\Omega^{-1}$ $\mathrm{cm}^{2} \mathrm{eq}^{-1}$ ) of $1.0 \mathrm{M}-\mathrm{H}_{2} \mathrm{SO}_{4}$ solution of
specific conductance $2.6 \times 10^{-1} \mathrm{~cm}^{-1}$, is
(a) $1.3 \times 10^{2}$
(b) $6.5 \times 10^{1}$
(c) $1.3 \times 10^{-1}$
(d) $2.6 \times 10^{2}$

Narayan Hari

Numerade Educator

Problem 117

The molar conductance of a $0.01 \mathrm{M}$ solution of acetic acid was found to be $16.30 \Omega^{-1} \mathrm{~cm}^{-1} \mathrm{~mol}^{-1}$ at $25^{\circ} \mathrm{C}$. The ionic
conductances of hydrogen and acetate ions at infinite dilution are $349.8$ and $40.9 \Omega^{-1}$ $\mathrm{cm}^{-1} \mathrm{~mol}^{-1}$, respectively, at the same temperature. What percentage of acetic acid is dissociated at this concentration?
(a) $0.04172 \%$
(b) $4.172 \%$
(c) $41.72 \%$
(d) $0.4172 \%$

Hast Aggarwal

Numerade Educator

Problem 118

The distance between two electrodes of a cell is $2.5 \mathrm{~cm}$ and area of each electrode is $5 \mathrm{~cm}^{2}$. The cell constant is
(a) $0.5 \mathrm{~m}^{-1}$
(b) $12.5 \mathrm{~cm}^{3}$
(c) $2.0 \mathrm{~cm}$
(d) $50 \mathrm{~m}^{-1}$

Dading Chen

Numerade Educator

Problem 119

The molar conductivity of $\mathrm{NH}_{4} \mathrm{Cl}, \mathrm{OH}^{-}$ and $\mathrm{Cl}^{-}$ at infinite dilution is 150,200 and $75 \Omega^{-1} \mathrm{~cm}^{2} \mathrm{~mol}^{-1}$, respectively. If the molar conductivity of a $0.01 \mathrm{M}-\mathrm{NH}_{4} \mathrm{OH}$
solution is $22 \Omega^{-1} \mathrm{~cm}^{2} \mathrm{~mol}^{-1}$, then its degree of dissociation is
(a) $0.146$
(b) $0.063$
(c) $0.080$
(d) $0.293$

Narayan Hari

Numerade Educator

Problem 120

Calculate the ionic product of water $25^{\circ} \mathrm{C}$ from the following data:
Conductivity of water $=5.5$ $\times 10^{-6} \mathrm{mhom}^{-1}$
$\lambda_{H}^{0}{ }^{+}=0.035 \mathrm{mho} \mathrm{m}^{2} \mathrm{~mol}^{-1}$
$\lambda_{\text {o? }}^{\circ}=0.020$ mho $\mathrm{m}^{2} \mathrm{~mol}^{-1}$
(a) $2 \times 10^{-14} \mathrm{M}^{2}$
(b) $1 \times 10^{-7} \mathrm{M}^{2}$
$1 \times 10^{-8} \mathrm{M}^{2}$

ra

Raj Aggarwal

Numerade Educator

Problem 121

Calculate $K_{a}$ of acetic acid if its $0.05 \mathrm{M}$ solution has molar conductivity of $7.814$ $\times 10^{-4} \Omega^{-1} \mathrm{~m}^{2} \mathrm{~mol}^{-1}$ at $25^{\circ} \mathrm{C}$. Given: $\Lambda_{\mathrm{m}}^{\circ}$ for
$\mathrm{CH}_{3} \mathrm{COOH}=3.907 \times 10^{-2} \Omega^{-1} \mathrm{~m}^{2} \mathrm{~mol}^{-1}$
(a) $2 \times 10^{-5}$
(b) $1.8 \times 10^{-5}$
(c) $4 \times 10^{-4}$
(d) $0.02$

Hast Aggarwal

Numerade Educator

Problem 122

Equal volumes of $0.015 \mathrm{M}-\mathrm{CH}_{3} \mathrm{COOH}$
and $0.015 \mathrm{M}-\mathrm{NaOH}$ solutions are mixed together. What would be the molar conductivity of mixture if conductivity of $\mathrm{CH}_{3} \mathrm{COONa}$ is $6.3 \times 10^{-4} \mathrm{~S} \mathrm{~cm}^{-1}$ ?
(a) $0.84 \mathrm{~S} \mathrm{~cm}^{2} \mathrm{~mol}^{-1}$
(b) $8.4 \mathrm{~S} \mathrm{~cm}^{2} \mathrm{~mol}^{-1}$
(c) $84 \mathrm{~S} \mathrm{~cm}^{2} \mathrm{~mol}^{-1}$
(d) $42 \mathrm{~S} \mathrm{~cm}^{2} \mathrm{~mol}^{-1}$

Narayan Hari

Numerade Educator

Problem 123

Calculate $\Lambda_{\mathrm{m}}^{-}$ (in $\Omega^{-1} \mathrm{~cm}^{2} \mathrm{~mol}^{-1}$ ) for $\mathrm{SrCl}_{2}$
at $25^{\circ} \mathrm{C}$, from the following data:
\begin{tabular}{|c|c|c|}
\hline Conc. & $0.25 \mathrm{M}$ & $1.0 \mathrm{M}$ \\
\hline$\Lambda_{\mathrm{m}}\left(\right.$ in $\left.\Omega^{-1} \mathrm{~cm}^{2} \mathrm{~mol}^{-1}\right)$ & 260 & 250 \\
\hline
\end{tabular}
(a) 270
(b) 265
(c) 240
(d) 275

Susan Hallstrom

Susan Hallstrom

Numerade Educator

Problem 124

The resistance of a solution $\mathrm{A}$ is $50 \Omega$ and that of solution $\mathrm{B}$ is $100 \Omega$, both solutions being taken in the same conductivity cell. If equal volumes of solution $\mathrm{A}$ and $\mathrm{B}$ are mixed, what will be the resistance of the mixture using the same cell? Assume that there is no increase in the degree of dissociation of $A$ and $B$ on mixing.
(a) $150 \Omega$
(b) $75 \Omega$
(c) $33.33 \Omega$
(d) $66.67 \Omega$

Nidhi Singhi

Numerade Educator

Problem 125

In a conductivity cell, the two platinum electrodes, each of area $10 \mathrm{~cm}^{2}$ are fixed $1.5 \mathrm{~cm}$ apart. The cell contained $0.05 \mathrm{~N}$ solution of a salt. If the two electrodes are just half dipped into the solution which has a resistance of $50 \Omega$, the equivalent conductance of the salt solution, in $\Omega^{-1}$ $\mathrm{cm}^{2} \mathrm{eq}^{-1}$, is
(a) 120
(b) 60
(c) 240
(d) 3000

Narayan Hari

Numerade Educator