Electrochemistry - class-XII

electrochemistry

46 Questions Published

Questions

Question 1 Multiple Choice (Single Answer)

What do you mean by equivalent Conductivity?

  1. It is defined as the conducting power of all the ions produced by dissolving one gram equivalent of an electrolyte in solution.
  2. It is defined as the conducting power of all the ions produced by dissolving ten gram equivalent of an electrolyte in solution.
  3. It is defined as the conducting power of all the ions produced by dissolving hundred gram equivalent of an electrolyte in solution.
  4. It is defined as the conducting power of all the ions produced by dissolving thousand gram equivalent of an electrolyte in solution.
Question 2 Multiple Choice (Single Answer)

The resistance of $1\ N$ solution of $CH _{3}COOH$ is $250\ ohm$ when measured in a cell of cell constant $1.15\ cm^{-1}$. The equivalent conductance will be:

  1. $4.6\ ohm^{-1} cm^{2} eq^{-1}$
  2. $9.2\ ohm^{-1} cm^{2} eq^{-1}$
  3. $18.4\ ohm^{-1} cm^{2} eq^{-1}$
  4. $0.023\ ohm^{-1} cm^{2} eq^{-1}$
Question 3 Multiple Choice (Single Answer)

The specific conductance of a $0.01\ M$ solution of $KCl$ is $0.0014\ ohm^{-1} cm^{-1}$ at $25^{\circ}C$. Its equivalent conductance is____________.

  1. $14$
  2. $140$
  3. $1.4$
  4. $0.14$
Question 4 Multiple Choice (Single Answer)

The resistance of a N/10 KCI solution is 245$\Omega $. Calculate the equivalent conductance of the solution if the electrodes in the cell are 4cm apart and each having an area of 7.0sq,cm.

  1. $23.32S{ cm }^{ 2 }{ eq }^{ -1 }$
  2. $23.23S{ cm }^{ 2 }{ eq }^{ -1 }$
  3. $2.332S{ cm }^{ 2 }{ eq }^{ -1 }$
  4. none of these
Question 5 Multiple Choice (Single Answer)

The equivalent conductance of a weak monobasic acid at infinite dilution is $100cm^3$ $eq^{-1}$ and that of its $0.01$M solution is $5cm^2$ $eq^{-1}$ at $25^o$C. The dissociation constant $K _a$ of the acid is:

  1. $2.5\times 10^{-4}$
  2. $5\times 10^{-4}$
  3. $1.25\times 10^{-5}$
  4. $2.5\times 10^{-5}$
Question 6 Multiple Choice (Single Answer)

Equivalent conductance and molar conductance of $Fe _2(SO _4) _3$ are related?

  1. $\bigwedge _e=\bigwedge _m$
  2. $\bigwedge _{eq} = \dfrac{\bigwedge _m}{3}$
  3. $\bigwedge _{eq} = 3 \bigwedge _m$
  4. $\bigwedge _{eq} = \dfrac{\bigwedge _m}{6}$
Question 7 Multiple Choice (Single Answer)

Molar ionic conductance of ${Ca}^{+2}$ is $x$ $S{m}^{2}$ ${mole}^{-1}$. Equivalent conductance of calcium phosphate is ____ $S{m}^{2}g$ ${eq}^{-1}$

  1. $x+y$
  2. $(3x+2y)$
  3. $6(3x+2y)$
  4. $\cfrac{3x+2y}{6}$
Question 8 Multiple Choice (Single Answer)

Which of the following has least conductivity in aqueous solution?

  1. $CO(NH _3) _4Cl _3$
  2. $Co(NH _3) _3Cl _3$
  3. $Co(NH _3) _5Cl _3$
  4. $Co(NH _3) _6Cl _3$
Question 9 Multiple Choice (Single Answer)

The equivalent conductance of $CH _3COONa, \ HCl$ and $NaCl$ at infinite dilution are $91, 426$ and $126 \ S \ cm^3 \ eq^{-1}$ respectively at $25^oC$. The equivalent conductance of $1 \ M \ CH _3COOH$ solution is $19.55 \ S \ cm^2 \ eq^{-1}$. The pH of the solution is:

  1. $5.3$
  2. $4.3$
  3. $2.3$
  4. $1.3$
Question 10 Multiple Choice (Single Answer)

The electrolytic conductance is a direct measure of:

  1. resistance
  2. potential
  3. concentration
  4. dissociation
Question 11 Multiple Choice (Single Answer)

Equivalent conductance of $BaCl _2, H _2SO _4$ and $HCl$ are $x _1, x _2$ and $x _3 S cm^2 equiv^{-1}$ at infinite dilution.If specific conductance of saturated $BaSO _4$ solution is of $y S cm^1$ then $K _{sp}$ of $BaSO _4$ is:

  1. $\frac{10^3y}{2(x _1 + x _2 - 2x _3)}$
  2. $\frac{10^6y^2}{4(x _1 + x _2 - 2x _3)^2}$
  3. $\frac{10^6y^2}{2(x _1 + x _2 - x _3)^2}$
  4. $\frac{x _1 + x _2 - 2x _3}{10^6y^2}$
Question 12 Multiple Choice (Single Answer)

For $HCl$ solution at ${25}^{o}C$ equivalent conductance at infinite dilution is $425 \ {ohm}^{-1}{cm}^{2}{equiv}^{-1}$. The specific conductance of a solution of $HCl$ is $3.825$ ${ohm}^{-1}{cm}^{-1}$. If the apparent degree of dissociation is $90$% the normality of the solution is :

  1. $0.90N$
  2. $1.0N$
  3. $10\ N$
  4. $1.2N$
Question 13 Multiple Choice (Single Answer)

The equivalent conductivity of $0.1 N \ CHNCH _{3}COOH$ at $25^{0}C$ is 80 and at infinite dilution it is 400, the degree of dissociation of $CH _{3}COOH$ is :

  1. 1
  2. 0.2
  3. 0.1
  4. 0.5
Question 14 Multiple Choice (Single Answer)

In infinite dilusions, the equivalent conductances of $Ba^{2+}$ and $Cl^{-}$ are $127$ and $76 ohm^{-1} , cm^{-1} , eqvt^{-1}$. The equivalent conductivity of $BaCl _2$ at indefinite dilution is?

  1. $101.5$
  2. $203.5$
  3. $139.5$
  4. $279.5$
Question 15 Multiple Choice (Single Answer)

${\text{N}}{{\text{a}} _{\text{3}}}{\text{Al}}{{\text{F}} _{\text{6}}},,$ is added to $,{\text{A}}{{\text{l}} _{\text{2}}}{{\text{O}} _{\text{3}}}$

  1. Improve the electrical conductivity of the cell
  2. Increases rate of production
  3. Increases the melting point
  4. Decrease the electrical conductivity
Question 16 Multiple Choice (Single Answer)

The equivalent conductance of $0.02$ M acctic acid  $1.62.*{10^{ - 3}}$.  Degree of ironisation $'a'$ of $C{H _3}COOH$ is:
$({x _H} = 349.83oh{m^{ - 1}}and\lambda C{H _3}CO{O^ - } = 40.89ohm{s^{ - 1}}$

  1. $0.01$
  2. $0.02$
  3. $0.03$
  4. $0.04$
Question 17 Multiple Choice (Single Answer)

Equivalent conductivity of $BaCl _2,H _2SO _4$ and HCI, are $x _1,x _2$ and $x _3scm^{-1}eq^{-1}$ at infinite dilution. If conductivity of saturated $BaSO _4$ solution is x $Scm^{-1}$, then $K _{sp}$ of $BaSO _4$ is

  1. $\dfrac {500x} {(x _1+x _2-2x _3)}$
  2. $\dfrac {10^6x^2} {(x _1+x _2-2x _3)^3}$
  3. $\dfrac {2.5\times10^5 x^2} {x _1-2x _2-x _3)^2}$
  4. $\dfrac {0.25 x^2} {x _1 + x _2-x _3)^2}$
Question 18 Multiple Choice (Single Answer)

Molar conductance of $C{a^{2 + }}$ and $C{l^ - }$ are  $120,c{m^2},$ $mo{l^{ - 1}}$ and $77,S,c{m^2},mo{l^{ - 1}}$ respectively. What is the equivalent conductance of $CaC{l _2}$ ?

  1. $98.5\,Sc{m^2}e{q^{ - 1}}$
  2. $137\,Sc{m^2}e{q^{ - 1}}$
  3. $197\,Sc{m^2}e{q^{ - 1}}$
  4. $247\,Sc{m^2}e{q^{ - 1}}$
Question 19 Multiple Choice (Single Answer)

At infinite dilution equivalent conductance of ${B^{ + 2}}$ & CI ions are 127  &  76$oh{m^{ - 1}}$ $c{m^{ - 1}}$` $e{q^{ - 1}}$ respectively. Equivalent conductance  of $BaC{I _2}$ at infinite diluition is : 

  1. 139.5
  2. 101.5
  3. 203
  4. 279
Question 20 Multiple Choice (Single Answer)

Equivalent constant of standard $BaSO _{4}$ is $400ohm^{-1}\ cm^{2}$ equiv$^{-1}$ and specific conduction is $8\times 10^{-5}\ ohm^{-1}\ cn^{-1}$. Hence $K _{SP}$ of $BaSO _{4}$ is

  1. $4\times 10^{-8}M^{2}$
  2. $1\times 10^{-8}M^{2}$
  3. $2\times 10^{-4}M^{2}$
  4. $1\times 10^{-4}M^{2}$
Question 21 Multiple Choice (Single Answer)

Which of the following is correct regarding current carrying ions in the solution of $C _{2}H _{5}COOH$ upon dilution?

  1. The number of ions in $1 cm^{3}$, as well as in total volume increases.
  2. The number of ions in $1 cm^{3}$ decreases, whereas that in the total volume remains constant.
  3. The number of ions in $1 cm^{3}$ decreases, but that in the total volume increases.
  4. The number of ions in $1 cm^{3}$, as well as in total volume decreases.
Question 22 Multiple Choice (Single Answer)

The resistance of $N/2$ solution of an electrolyte in a cell was found to be $45$ ohm. The equivalent conductivity of a solution, if the electrodes in the cell are $2.2$ cm apart and have an area of $3.8 cm^2$ will be:

  1. $52.72\ S cm^2 eq^{-1}$
  2. $22.57\ S cm^2 eq^{-1}$
  3. $27.52\ S cm^2 eq^{-1}$
  4. $25.72\ S cm^2 eq^{-1}$
Question 23 Multiple Choice (Single Answer)

The resistance of 0.1 N solution of a salt is found to be $2.5\times10^{3}$. The equivalent conductance of the solution is: (cell constant=1.15 $cm^{-1}$)

  1. 3.6
  2. 4.6
  3. 5.6
  4. 6.6
Question 24 Multiple Choice (Single Answer)

At 291 K, the equivalent conductivities at infinite dilution of $NH _4Cl$, $NaOH $ and $NaCl $ are $129.8$, $217.5$ and $108.9$ S $cm^2 eq^{-1}$ respectively. The equivalent conductivity at infinite dilution of $NH _4OH$ is:

  1. $208.4 S cm^2 eq^{-1}$
  2. $238.4 S cm^2 eq^{-1}$
  3. $283.4 S cm^2 eq^{-1}$
  4. None of these
Question 25 Multiple Choice (Single Answer)

The correct order of equivalent conductivity at infinite dilution of $LiCl,\ NaCl$ and $KCl$ is:

  1. $LiCl > NaCl > KCl$
  2. $KCl > NaCl > LiCl$
  3. $NaCl > KCl > LiCl$
  4. $LiCl > KCl > NaCl$
Question 26 Multiple Choice (Single Answer)

$\lambda _{eq}$ x Normality = __________

  1. K x 10$^3$
  2. K x 10$^4$
  3. K x 10$^5$
  4. K x 10$^6$
Question 27 Multiple Choice (Single Answer)

Equivalent conductance of an electrolyte containing $NaF$ at infinite dilution is $90.1\ Ohm^{-1} cm^{2}$. If $NaF$ is replaced by $KF$ what is the value of equivalent conductance?

  1. $90.1\ Ohm^{-1} cm^{2}$
  2. $11.2\ Ohm^{-1} cm^{2}$
  3. $0$
  4. $222.4\ Ohm^{-1} cm^{2}$
Question 28 Multiple Choice (Single Answer)

The resistance of $N/10$ solution is found to be $2.5\times 10^{3}ohm$. The equivalent conductance of the solution is (cell constant $= 1.25\ cm^{-1})$.

  1. $2.5\ ohm^{-1} cm^{2} equiv^{-1}$
  2. $5\ ohm^{-1} cm^{2} equiv^{-1}$
  3. $2.5\ ohm^{-1} cm^{-2} equiv^{-1}$
  4. $5\ ohm^{-1} cm^{-2} equiv^{-1}$
Question 29 Multiple Choice (Single Answer)

What are the units of equivalent conductivity of a solution?

  1. $mho\ cm^{-1}$
  2. $ohm\ cm^{-1} g\ equiv^{-1}$
  3. $mho\ cm^{-2}g\ equiv^{-1}$
  4. $mho\ cm^{2}g\ equiv^{-1}$
Question 30 Multiple Choice (Single Answer)

The equivalent conductances of $NaCl$ at concentration $c$ and at infinite dilution are $\lambda _{c}$ and $\lambda _{\infty}$ respectively. The correct relationship between $\lambda _{c}$ and $\lambda _{\infty}$ is given as: (where the constant $b$ is positive).

  1. $\lambda _{c} = \lambda _{\infty} - b\sqrt {c}$
  2. $\lambda _{c} = \lambda _{\infty} + b\sqrt {c}$
  3. $\lambda _{c} = \lambda _{\infty} + bc$
  4. $\lambda _{c} = \lambda _{\infty} - bc$
Question 31 Multiple Choice (Single Answer)

The equivalent conductances at infinite dilution of $HCl$ and $NaCl$ are $426.15$ and $126.15\ mho\ cm^{2}g\ eq^{-1}$ respectively. If can be said that the mobility of:

  1. $H^{+}$ ions is much more than that of $Cl^{-}$ ions
  2. $Cl^{-}$ ions is much more than that of $H^{+}$ ions
  3. $H^{+}$ ions is much more than that of $Na^{+}$ ions
  4. $Na^{+}$ ions is much more than that of $H^{+}$ ions
Question 32 Multiple Choice (Single Answer)

The resistance of $0.01\ N$ solution at $25^{\circ}$ is $200\ ohm$. Cell constant of the conductivity cell is unity. Calculate the equivalent conductance of the solution.

  1. $200\ ohm^{-1}cm^{2} eq^{-1}$.
  2. $300\ ohm^{-1}cm^{2} eq^{-1}$.
  3. $400\ ohm^{-1}cm^{2} eq^{-1}$.
  4. $500\ ohm^{-1}cm^{2} eq^{-1}$.
Question 33 Multiple Choice (Single Answer)

The specific conductance $(K)$ of an electrolyte of $0.1\ N$ concentration is related to equivalent conductance $(\wedge _{e})$ by the following formula.

  1. $\wedge _{e} = K$
  2. $\wedge _{e} = 10 K$
  3. $\wedge _{e} = 100 K$
  4. $\wedge _{e} = 10000 K$
Question 34 Multiple Choice (Single Answer)

The specific conductivity of $0.1$ $N$ $KCl$ solution at $20^0$C is $0.0212$ $ohm^{-1} cm^{-1}$. The solution was found to offer resistance of $55$ ohms. Find the cell constant of the conductivity cell.

  1. $2.25$
  2. $1.166$
  3. $1.936$
  4. none of these
Question 35 Multiple Choice (Single Answer)

What would be the equivalent conductivity of a cell in which $0.5$ N salt solution offers a resistance of $40$ ohm whose electrodes are $2$ cm apart and $5$ $cm^{2}$ in area?

  1. $10$ $ohm^{-1}$ $cm^2$ $eq^{-1}$
  2. $20$ $ohm^{-1}$ $cm^{2}$ $eq^{-1}$
  3. $30$ $ohm^{-1}$ $cm^{2}$ $eq^{-1}$
  4. $25$ $ohm^{-1}$ $cm^{2}$ $eq^{-1}$
Question 36 Multiple Choice (Single Answer)

The equivalent conductivity of $N/10$ solution of acetic acid at $25^o$C is $14.3$ $ohm^{-1}$ $cm^2$ $equiv^{-1}$. What will be the degree of dissociation of acetic acid?
$(\Lambda _{\infty CH _3COOH}=390.71$ $ohm^{-1}$ $cm^2$ $equiv^{-1}$).

  1. $3.66\%$
  2. $3.9\%$
  3. $2.12\%$
  4. $0.008\%$
Question 37 Multiple Choice (Single Answer)

Which of the following statements is true?

  1. When an aqueous solution of NaCl is electrolysed, sodium metal is deposited at cathode
  2. There is no difference between specific conductivity and molar conductivity
  3. Silver nitrate solution can be stored in a copper container
  4. The addition of liquid bromine to iodide solution turns it violet
Question 38 Multiple Choice (Single Answer)

The ionic conductivity of $B{a^{2 + }}$ and $C{l^ - }$ at infinite dilution are 127 and 76 respectively. The equivalent conductivity of $BaC{l _2}$ at infinite dilution (in $oh{m^ - },c{m^2},e{q^{ - 1}}$) would be:

  1. 279
  2. 280
  3. 139.5
  4. 102
Question 39 Multiple Choice (Single Answer)

The correct order of equivalent conductance at infinite dilution of LiCl, NaCl and KCl is:

  1. LiCl $>$ NaCl $>$ KCl
  2. KCl $>$ NaCl $>$ LiCl
  3. NaCl $>$ KCl $>$ LiCl
  4. LiCl $>$ KCl $>$ NaCl
Question 40 Multiple Choice (Single Answer)

The equivalent conductivity conductivity of 1M ${{\text{H}} _{\text{2}}}{\text{S}}{{\text{O}} _{\text{4}}}$ solution would be if specific conductance is ${\text{26}} \times {\text{1}}{{\text{0}}^{ - 2}}{\text{S}},{\text{c}}{{\text{m}}^{ - 1}}$.

  1. $1.3 \times {10^2}{\text{S}}\,{\text{c}}{{\text{m}}^2}\,{\text{e}}{{\text{q}}^{ - 1}}$
  2. $1.6 \times {10^2}{\text{S}}\,{\text{c}}{{\text{m}}^2}\,$
  3. $13\,{\text{S}}\,{\text{c}}{{\text{m}}^2}\,{\text{mo}}{{\text{l}}^{{\text{ - 1}}}}$
  4. $1.3 \times {10^3}{\text{S}}\,{\text{c}}{{\text{m}}^2}\,{\text{mo}}{{\text{l}}^{ - 1}}$
Question 41 Multiple Choice (Single Answer)

Equivalent conductance at infinite dilution for weak electrolyte HF:

  1. can be determined by measurement of equivalent conductance at infinite dilution for dilute solution of $HCL, \; HBr$ and $HI$
  2. can be determined by measurement of equivalent conductance at infinite dilution for very dilute $HF$ solutions
  3. can best be determined from measurements on dilute
  4. can not be calculated
Question 42 Multiple Choice (Single Answer)

The conductivity of a saturated solution of $Ba{ SO } _{ 4 }$ is $306\times { 10 }^{ -6 }{ ohm }^{ -1 }{ cm }^{ -1 }$ and its equivalent conductance is $1.53 \ { ohm }^{ -1 }{ cm }^{ 2 }{ equiv }^{ -1 }$. 


The ${ K } _{ sp }$ for ${ BaSO } _{ 4 }$ will be :

  1. $4\times { 10 }^{ -12 }$
  2. $2.5\times { 10 }^{ -9 }$
  3. $2.5\times { 10 }^{ -13 }$
  4. $4\times { 10 }^{ -6 }$
Question 43 Multiple Choice (Single Answer)

If the specific resistance of a solution of concentration C g equivalent/litre is R, then its equivalent conductance is:

  1. $\dfrac{100R}{C}$
  2. $\dfrac{RC}{1000}$
  3. $\dfrac{1000}{RC}$
  4. $\dfrac{C}{1000R}$
Question 44 Multiple Choice (Single Answer)

The resistance of $0.2\ M$ solution of an electrolyte is $50\ \Omega$.The specific conductance of the solution is $1.3\ S\ m^{-1}$. If the resistance of the $0.4\ M$ solution of the same electrolyte is $260\ \Omega$, its molar conductivity is :

  1. $62.5\ S\ m^{2} mol^{-1}$
  2. $6250\ S\ m^{2} mol^{-1}$
  3. $6.25\ \times10^{-4}S\ m^{2} mol^{-1}$
  4. $625\times10^{-4}\ S\ m^{2} mol^{-1}$
Question 45 Multiple Choice (Single Answer)

The equivalent conductivity of monobasic acid at infinite dilution is 348 $ohm^{-1}$ $cm^2$ $eq^{-1}$. If the resistivity of the solution containing 15 g acid (molar mass 49) in 1 litre is 18.5 ohm cm, what is the degree of dissociation of acid?

  1. 45.9%
  2. 40.2%
  3. 60.4%
  4. 50.7%
Question 46 Multiple Choice (Single Answer)

The conductivities at infinite dilution of ${\text{N}}{{\text{H}} _{\text{4}}}{\text{Cl,NaOH}}$ and $\text{NaCl}$ are 130, 218, 120 ${\text{oh}}{{\text{m}}^{{\text{ - 1}}}}{\text{c}}{{\text{m}}^{\text{2}}}{\text{e}}{{\text{q}}^{{\text{ - 1}}}}$. If equivalent conductance of N/100 solution of ${\text{N}}{{\text{H}} _{\text{4}}}{\text{OH}}$ is 10, then degree of dissociation of ${\text{N}}{{\text{H}} _{\text{4}}}{\text{OH}}$ at this dilution is:

  1. 0.005
  2. 0.043
  3. 0.01
  4. 0.02