Electrochemistry MCQ Questions & Answers in Physical Chemistry | Chemistry

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101. Standard electrode potential for $$\frac{{S{n^{4 + }}}}{{S{n^{2 + }}}}$$  couple is $$ + 0.15\,V$$  and that for the $$\frac{{C{r^{3 + }}}}{{Cr}}$$  couple is $$ - 0.74.$$  These two couples in their standard state are connected to make a cell. The cell potential will be

A $$ + 0.89\,V$$
B $$ + 0.18\,V$$
C $$ + 1.83\,V$$
D $$ + 1.199\,V$$
Answer :   $$ + 0.89\,V$$

102. Same amount of electric current is passed through the solutions of $$AgN{O_3}$$  and $$HCl.$$  If $$1.08\,g$$  of silver is obtained from $$AgN{O_3}$$  solution, the amount of hydrogen liberated at $$STP$$  will be

A 1.008 $$g$$
B 11.2 $$g$$
C 0.01 $$g$$
D 1.1 $$g$$
Answer :   0.01 $$g$$

103. A smuggler could not carry gold by depositing iron on the gold surface since

A gold is denser
B iron rusts
C gold has higher reduction potential than iron
D gold has lower reduction potential than iron
Answer :   gold has higher reduction potential than iron

104. Limiting molar conductivity of $$N{H_4}OH$$  $$\left( {{\text{i}}{\text{.e}}{\text{.}}\,\,{{\mathop \Lambda \limits^o }_{m\,\,\left( {N{H_4}OH} \right)}}} \right)$$    is equal to

A \[{{\overset{\circ }{\mathop{\Lambda }}\,}_{m\,\,\left( N{{H}_{4}}Cl \right)}}+{{\overset{\circ }{\mathop{\Lambda }}\,}_{m\,\,\left( NaCl \right)}}-{{\overset{\circ }{\mathop{\Lambda }}\,}_{m\,\,\left( NaOH \right)}}\]
B \[{{\overset{\circ }{\mathop{\Lambda }}\,}_{m\,\,\left( NaOH \right)}}+{{\overset{\circ }{\mathop{\Lambda }}\,}_{m\,\,\left( NaCl \right)}}-{{\overset{\circ }{\mathop{\Lambda }}\,}_{m\,\,\left( N{{H}_{4}}Cl \right)}}\]
C \[{{\overset{\circ }{\mathop{\Lambda }}\,}_{m\,\,\left( N{{H}_{4}}OH \right)}}+{{\overset{\circ }{\mathop{\Lambda }}\,}_{m\,\,\left( N{{H}_{4}}Cl \right)}}-{{\overset{\circ }{\mathop{\Lambda }}\,}_{m\,\,\left( HCl \right)}}\]
D \[{{\overset{\circ }{\mathop{\Lambda }}\,}_{m\,\,\left( N{{H}_{4}}Cl \right)}}+{{\overset{\circ }{\mathop{\Lambda }}\,}_{m\,\,\left( NaOH \right)}}-{{\overset{\circ }{\mathop{\Lambda }}\,}_{m\,\,\left( NaCl \right)}}\]
Answer :   \[{{\overset{\circ }{\mathop{\Lambda }}\,}_{m\,\,\left( N{{H}_{4}}Cl \right)}}+{{\overset{\circ }{\mathop{\Lambda }}\,}_{m\,\,\left( NaOH \right)}}-{{\overset{\circ }{\mathop{\Lambda }}\,}_{m\,\,\left( NaCl \right)}}\]

105. The highest electrical conductivity of the following aqueous solutions is of

A $$0.1 M$$  difluoroacetic acid
B $$0.1 M$$  fluoroacetic acid
C $$0.1 M$$  chloroacetic acid
D $$0.1 M$$  acetic acid
Answer :   $$0.1 M$$  difluoroacetic acid

106. $${\text{Given}}:E_{\frac{{C{r^{3 + }}}}{{Cr}}}^ \circ = - 0.74\,V;$$      $$E_{\frac{{MnO_4^ - }}{{M{n^{2 + }}}}}^ \circ = 1.51\,V$$
$$E_{\frac{{C{r_2}O_7^{2 - }}}{{C{r^{3 + }}}}}^ \circ = 1.33\,V;E_{\frac{{Cl}}{{C{l^ - }}}}^ \circ = 1.36\,V$$
Based on the data given above, strongest oxidising agent will be:

A $$Cl$$
B $${C{r^{3 + }}}$$
C $${M{n^{2 + }}}$$
D $$MnO_4^ - $$
Answer :   $$MnO_4^ - $$

107. Standard electrode potentials are
$$\eqalign{ & \frac{{F{e^{2 + }}}}{{Fe}},\,{E^ \circ } = - 0.44\,V \cr & \frac{{F{e^{3 + }}}}{{F{e^{2 + }}}},\,{E^ \circ } = 0.77\,V \cr} $$
$$F{e^{2 + }},F{e^{3 + }}$$   and $$Fe$$  block are kept together, then

A $$F{e^{3 + }}$$  increases
B $$F{e^{3 + }}$$  decreases
C $$\frac{{F{e^{2 + }}}}{{F{e^{3 + }}}}$$  remains unchanged
D $$F{e^{2 + }}$$  decreases
Answer :   $$F{e^{3 + }}$$  decreases

108. The standard e.m.f. of a cell involving one electron change is found to be $$0.591 V$$  at $${25^ \circ }C.$$ The equilibrium constant of the reaction is $$\left( {F = 96500\,C\,mo{l^{ - 1}};R = 8.314\,J{K^{ - 1}}\,mo{l^{ - 1}}} \right)$$

A 1.0 × 1010
B 1.0 × 105
C 1.0 × 101
D 1.0 × 1030
Answer :   1.0 × 1010

109. $${\Delta _r}{G^ \circ }$$  for the cell with the cell reaction : $$Z{n_{\left( s \right)}} + A{g_2}{O_{\left( s \right)}} + {H_2}{O_{\left( l \right)}} \to $$       $$Zn_{\left( {aq} \right)}^{2 + } + 2A{g_{\left( s \right)}} + 2OH_{\left( {aq} \right)}^ - $$
$$\left[ {E_{\frac{{A{g_2}O}}{{Ag}}}^ \circ = 0.344\,V,E_{\frac{{Z{n^{2 + }}}}{{Zn}}}^ \circ = - 0.76\,V} \right]$$

A $$2.13 \times {10^5}\,J\,mo{l^{ - 1}}$$
B $$ - 2.13 \times {10^5}\,J\,mo{l^{ - 1}}$$
C $$1.06 \times {10^5}\,J\,mo{l^{ - 1}}$$
D $$ - 1.06 \times {10^5}\,J\,mo{l^{ - 1}}$$
Answer :   $$ - 2.13 \times {10^5}\,J\,mo{l^{ - 1}}$$

110. The equivalent conductances of $$B{a^{2 + }}$$  and $$C{l^ - }$$  are $$127$$  and $$76\,{\Omega ^{ - 1}}\,c{m^{ - 1}}\,e{q^{ - 1}}$$    respectively at infinite dilution. The equivalent conductance of $$BaC{l_2}$$  at infinite dilution will be

A 139.52
B 203
C 279
D 101.5
Answer :   139.52