Ionic Conductance

Q. The conductivity of a weak acid $HA$ of concentration $0.001{\text{mol L}}^{-1}$ is $2.0\times {10}^{-5}Sc{m}^{-1}$.

If ${\Lambda }_m^o\left(HA\right)=190Sc{m}^2{\text{mol}}^{-1}$, the ionization constant $\left(K_a\right)$ of $HA$ is equal to ____ $\times {10}^{-6}$.
(Round off to the Nearest Integer)

Q. The specific conductance of $\frac{N}{10}KCl$ solution at ${20}^{\circ }C$ is $0.0212oh{m}^{-1}c{m}^{-1}$ and the resistance of cell containing this solution at ${20}^{\circ }C$ is 55 ohm. The cell constant is

1. $1.166c{m}^{-1}$
2. $2.173c{m}^{-1}$
3. $3.324c{m}^{-1}$
4. $4.616c{m}^{-1}$

Q. The equivalence conductances of sodium chloride, hydrochloric acid and sodium acetate at infinite dilution are $126.45,426.16$ and $91.0{\text{ohm}}^{-1}{\text{cm}}^2{\text{eq}}^{-1}$, respectively at $25{}^o\text{C}$.
Calculate the equivalent conductance $\left({\text{in ohm}}^{-1}{\text{cm}}^2{\text{eq}}^{-1}\right)$ of acetic acid at infinite dilution.

Q. The specific conductance of $\frac{N}{10}KCl$ solution at ${20}^{\circ }C$ is $0.0212oh{m}^{-1}c{m}^{-1}$ and the resistance of cell containing this solution at ${20}^{\circ }C$ is 55 ohm. The cell constant is

1. 1.166 cm^-1
2. 2.173 cm^-1
3. 3.324 cm^-1
4. 4.616 cm^-1

Q. The specific conductance of a $\frac{N}{10}KCl$ solution at ${18}^{0}C$ is $1.12\times {10}^{-2}mhoc{m}^{-1}$. The resistance of the soution contained in the cell is found to be $65ohm$. Calculate the cell constant:

1. $0.912c{m}^{-1}$
2. $0.512c{m}^{-1}$
3. $0.728c{m}^{-1}$
4. $0.632c{m}^{-1}$

Q. The cell constant of a given cell is $0.47c{m}^{-1}$. The resistance of a solution placed in this cell is measured to be $31.6ohm$. The conductivity of the solution in $Sc{m}^{-1}$ is:

1. 0.15
2. 1.5
3. 0.015
4. 150

Q. Cleansing action of soaps includes:

1. formation of micelles
2. emulsification of oil or grease
3. lowering of surface tension of water
4. all of the above

Q. Specific conductance of a decimolar solution of $KCl$ at $25{}^{\circ }\text{C}$ is $1.12{\text{S m}}^{-1}$. The resistance of a cell containing the solution at $25{}^{\circ }\text{C}$ was found to be $50\Omega$. The cell constant is:

1. $50{\text{m}}^{-1}$
2. $25{\text{m}}^{-1}$
3. $56{\text{m}}^{-1}$
4. $28{\text{m}}^{-1}$

Q. What is the ionization constant of crotonic acid if the conductivity of a $0.001M$ crotonic acid solution is $3.83\times {10}^{-5}{\Omega }^{-1}c{m}^{-1}$?

Limiting molar conductivities at ${25}^{o}C$:
$HCl=426{\Omega }^{-1}c{m}^{2}mo{l}^{-1}$
$NaCl=126{\Omega }^{-1}c{m}^{2}mo{l}^{-1}$
$NaC\text{(sodium crotonate)}=83{\Omega }^{-1}c{m}^{2}mo{l}^{-1}$.
(Crotonate ion is represented by $C^{-}$)

1. ${10}^{-3}$

2. $1.11\times {10}^{-5}$

3. $1.11\times {10}^{-4}$

4. $0.01$

Q. The cell constant of a given cell is $0.25c{m}^{-1}$. The resistance of a solution placed in this cell is measured to be $100ohm$. The conductivity of the solution in $Sc{m}^{-1}$ is:

1. $0.25Sc{m}^{-1}$
2. $0.025Sc{m}^{-1}$
3. $0.0025Sc{m}^{-1}$
4. None of the above

Q. Assertion :${\Lambda }_{eq\left(C{H}_{3}COOH\right)}^{\circ }$ cannot be determined experimentally. Reason: $C{H}_{3}COOH$ is a weak acid and Debye-Huckel Onsager equation cannot be used. Extrapolation method cannot be employed.

1. Both Assertion and Reason are correct and Reason is the correct explanation for Assertion
2. Both Assertion and Reason are correct but Reason is not the correct explanation for Assertion
3. Assertion is correct but Reason is incorrect
4. Assertion is incorrect but Reason is correct

Q. The molar conductivity at infinite dilution is called _____.

1. minimium molar conductivity
2. limiting molar conductivity
3. maximum molar conductivity
4. None of these

Q.

The emf of a concentration cell consisting of two zinc electrode, one dipping into M/4 solution of zinc sulphate and the other into M/16 solution of the same salt at 25${}^0$C :

1. 0.0125 V
2. 0.0250 V
3. 0.0178 V
4. 0.0356 V

Q. Equivalents of ${CO}_2$ used per mol of $H_{2}O$ used is :

1. $2$
2. $3$
3. $5$
4. $6$

Q. The resistance a solution A is 50 ohm and that of solution B is 100 ohm, both solutions are taken in the same conductivity cell. If equal volumes of solution A and B are mixed, what is the resistance of the mixture using the same cell? (Assume there is no change or increase in the α of A and B on mixing)

1. R = 66.67 ohm.
2. R = 86.67 ohm.
3. R = 96.67 ohm.
4. R = 76.67 ohm.

Q. The equivalent weight of chlorine molecule in the equation:
$3C{l}_2+6NaOH\to 5NaCl+NaCl{O}_3+3H_{2}O$

1. $59.1$
2. $42.6$
3. $71$
4. $35.5$

Q. The qualitative sketches I, II and III given below show the variation of surface tension with molar concentration of three different aqueous solutions of $KCl,C{H}_{3}OH$ and $C{H}_3(C{H}_2{)}_{11}OS{O}_3^{-}N{a}^{+}$ at room temperature. The correct assignment of the sketches is

1. I : KCl; II : $C{H}_{3}OH$;
   III : $C{H}_3(C{H}_2{)}_{11}OS{O}_3^{-}N{a}^{+}$
2. I : $C{H}_3(C{H}_2{)}_{11}OS{O}_3^{-}N{a}^{+}$;
   II : $C{H}_{3}OH$; III : $KCl$
3. I : $KCl$;
   II : $C{H}_3(C{H}_2{)}_{11}OS{O}_3^{-}N{a}^{+}$;
   III : $C{H}_{3}OH$
4. I : $C{H}_{3}OH$; II : $KCl$;
   III : $C{H}_3(C{H}_2{)}_{11}OS{O}_3^{-}N{a}^{+}$

Q. At infinite dilution, the molar conductance of $B{a}^{2+}$ and $C{l}^{-}$ are $127$and $76Sc{m}^{2}mo{l}^{-1}$. What is the molar conductivity ${\text{in S cm}}^2{\text{mol}}^{-1}$ of $BaC{l}_2$, at indefinite dilution?

Q. The equivalent conductance of $C_6{H}_{5}COONa,HCl$ and $NaCl$ at infinite dilution are $82.4,426.2$ and $126.5{\Omega }^{-1}{\text{cm}}^2$. Calculate the equivalent conductance $\left({\Omega }^{-1}{\text{cm}}^2\right)$ of benzoic acid at infinite dilution.

1. $217.3{\Omega }^{-1}{\text{cm}}^2$
2. $272.1{\Omega }^{-1}{\text{cm}}^2$
3. $191.05{\Omega }^{-1}{\text{cm}}^2$
4. $382.1{\Omega }^{-1}{\text{cm}}^2$

Q. Resistance of a $0.1NKCN$ solution is $245\Omega$. If the electrodes in the cell are $5cm$ apart and area having $100c{m}^2$ each, the molar conductance of the solution will be:

1. $204Sc{m}^{2}mo{l}^{-1}$
2. $2.04Sc{m}^{2}mo{l}^{-1}$
3. $20.4Sc{m}^{2}mo{l}^{-1}$
4. $0.204Sc{m}^{2}mo{l}^{-1}$

Q.

For a solution of an electrolyte at a particular concentration and temperature, which of the following is not the function of cell constant?

1) specific conductance

2) molar conductance

3) equivalent conductance

4) conductance

1. 1, 2
2. 1, 2, 3
3. 2, 3, 4
4. 1, 4

Q. The equivalent conductance 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. ${\lambda }_c={\lambda }_{\infty }+\left(B\right)C$
2. ${\lambda }_c={\lambda }_{\infty }-\left(B\right)C$
3. ${\lambda }_c={\lambda }_{\infty }-B\sqrt{C}$
4. ${\lambda }_c={\lambda }_{\infty }+B\sqrt{C}$

Q. The resistance of 0.5 M solution of an electrolyte in a conductivity cell was found to be 50 $\Omega$. If the electrodes in the conductivity cell are 2.2 cm apart and have an area of 4.4 $c{m}^2$ then the molar conductivity (in $S{m}^{2}mo{l}^{–1}$) of the solution is

1. 0.2
2. 0.02
   
3. 0.002
4. None of these

Q. The resistance a solution A is 50 ohm and that of solution B is 100 ohm, both solutions are taken in the same conductivity cell. If equal volumes of solution A and B are mixed, what is the resistance of the mixture using the same cell? (Assume there is no change or increase in the α of A and B on mixing)

1. R = 96.67 ohm.
2. R = 76.67 ohm.
3. R = 86.67 ohm.
4. R = 66.67 ohm.

Q. The specific conductance of $\frac{N}{10}KCl$ solution at ${20}^{\circ }C$ is $0.0212oh{m}^{-1}c{m}^{-1}$ and the resistance of cell containing this solution at ${20}^{\circ }C$ is 55 ohm. The cell constant is

1. $1.166c{m}^{-1}$
2. $2.173c{m}^{-1}$
3. $3.324c{m}^{-1}$
4. $4.616c{m}^{-1}$

Q.

The molar conductivities of ${\wedge }_{NaOAC}^0$ and ${\wedge }_{HCl}^0$ at infinite dilution in water at ${25}^{0}C$ and 91.0 and $426.2Sc{m}^2/mol$ respectively. To calculate ${\wedge }_{HOAc}^0$, the additional value required is:

1. ${\wedge }_{NaCl}^0$
2. ${\wedge }_{H_{2}O}^0$
3. ${\wedge }_{NaOH}^0$
4. ${\wedge }_{KCl}^0$

Q. An aqueous solution of $X$ is added slowly to an aqueous solution of $Y$ as shown in List I. The variation in conductivity of these reactions is given in List II. Match list I with List II and select the correct answer using the code given below the lists :

	List I		List II
P.	$(\underset{X}{C_2{H}_5{)}_{3}N}+\underset{Y}{C{H}_{3}COOH}$	1.	Conductivity decreases and then increases
Q.	$\underset{X}{KI\left(0.1M\right)}+\underset{Y}{AgN{O}_3\left(0.01M\right)}$	2.	Conductivity decreases and then does notchange much
R.	$\underset{X}{C{H}_{3}COOH}+\underset{Y}{KOH}$	3.	Conductivity increases and then does notchange much
S.	$\underset{X}{NaOH}+\underset{Y}{HI}$	4.	Conductivity does not change much andthen increases

	P	Q	R	S
(A)	3	4	2	1
(B)	4	3	2	1
(C)	2	3	4	1
(D)	1	4	3	2

1. $\left(B\right)$
2. $\left(D\right)$
3. $\left(C\right)$
4. $\left(A\right)$

Q. 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. ${\lambda }_c={\lambda }_{\infty }-bc$

Q. The equivalent conductance 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. ${\lambda }_C={\lambda }_{\infty }+\left(B\right)C$
2. ${\lambda }_C={\lambda }_{\infty }-\left(B\right)C$
3. ${\lambda }_C={\lambda }_{\infty }-\left(B\right)\sqrt{C}$
4. ${\lambda }_C={\lambda }_{\infty }+\left(B\right)\sqrt{C}$

Q. The qualitative sketches I, II and III given below show the variation of surface tension with molar concentration of three different aqueous solutions of $KCl,C{H}_{3}OH$ and $C{H}_3(C{H}_2{)}_{11}OS{O}_3^{-}N{a}^{+}$ at room temperature. The correct assignment of the sketches is

1. I : KCl; II : $C{H}_{3}OH$;
   III : $C{H}_3(C{H}_2{)}_{11}OS{O}_3^{-}N{a}^{+}$
2. I : $C{H}_3(C{H}_2{)}_{11}OS{O}_3^{-}N{a}^{+}$;
   II : $C{H}_{3}OH$; III : $KCl$
3. I : $KCl$;
   II : $C{H}_3(C{H}_2{)}_{11}OS{O}_3^{-}N{a}^{+}$;
   III : $C{H}_{3}OH$
4. I : $C{H}_{3}OH$; II : $KCl$;
   III : $C{H}_3(C{H}_2{)}_{11}OS{O}_3^{-}N{a}^{+}$