191. How many moles of $$Pt$$ may be deposited on the cathode when $$0.80\,F$$ of electricity is passed through a $$1.0\,M$$ solution of $$P{t^{4 + }}?$$
A
0.1 $$mol$$
B
0.2 $$mol$$
C
0.4 $$mol$$
D
0.6 $$mol$$
Answer :
0.2 $$mol$$
192. When an aqueous solution of $$AgN{O_3}$$ is electrolysed between platinum electrodes, the substances liberated at anode and cathode are
A
silver is deposited at cathode and $${O_2}$$ is liberated at anode
B
silver is deposited at cathode and $${H_2}$$ is liberated at anode
C
hydrogen is liberated at cathode and $${O_2}$$ is liberated at anode
D
silver is deposited at cathode and $$Pt$$ is dissolved in electrolyte.
Answer :
silver is deposited at cathode and $${O_2}$$ is liberated at anode
193.
$$1.0\,L$$ each of a buffer containing $$1\,mole$$ $$N{H_3}$$ and
$$1\,mole$$ of $$NH_4^ + $$ were placed in the cathodic and anodic half-cells and $$965\,C$$ of electricity was passed. If anodic and cathodic half cells reactions involve oxidation and reduction of water only as $$2{H_2}O \to 4{H^ + } + {O_2} - 4{e^ - };$$ $$2{H_2}O + 2{e^ - } \to {H_2} + 2O{H^ - }$$
Then $$pH$$ of
A
cathodic solution will increase
B
anodic solution will decrease
C
both the solutions will remain practically constant
D
both the solutions will increase
Answer :
both the solutions will remain practically constant
194. The ionic conductivity of $$B{a^{2 + }}$$ and $$C{l^ - }$$ at infinite dilution are $$127$$ and $$76\,oh{m^{ - 1}}\,c{m^2}\,e{q^{ - 1}}$$ respectively. The equivalent conductivity of $$BaC{l_2}$$ at infinity dilution $$\left( {{\text{in}}\,oh{m^{ - 1}}c{m^2}\,e{q^{ - 1}}} \right)$$ would be :
A
203
B
279
C
101.5
D
139.5
Answer :
279
195. A gas $$X$$ at $$1\,atm$$ is bubbled through a solution containing a mixture of $$1\,M\,{Y^ - }$$ and $$1\,M\,{Z^ - }$$ at $${25^ \circ }C.$$ If the reduction potential of $$Z > Y > X,$$ then
A
$$Y$$ will oxidise $$X$$ and not $$Z$$
B
$$Y$$ will oxidise $$Z$$ and not $$X$$
C
$$Y$$ will oxidise both $$X$$ and $$Z$$
D
$$Y$$ will reduce both $$X$$ and $$Z.$$
Answer :
$$Y$$ will oxidise $$X$$ and not $$Z$$
196. The pressure of $${H_2}$$ required to make the potential of $${H_2}$$ -electrode zero in pure water at $$298\,K$$ is
A
$${10^{ - 12}}atm$$
B
$${10^{ - 10}}atm$$
C
$${10^{ - 4}}atm$$
D
$${10^{ - 14}}atm$$
Answer :
$${10^{ - 14}}atm$$
197.
The given figure shows the corrosion of iron in atmosphere,
Fill in the blanks by choosing an appropriate option. At a particular spot of an object made of iron, $$\underline {\left( {\text{i}} \right)} $$ of iron to ferrous ion takes place and that spot behaves as $$\underline {\left( {{\text{ii}}} \right)} $$ . Electrons released at anodic spot move through the metal and go to another spot on the metal and reduce oxygen in presence of $${H^ + }.$$ This spot behaves as $$\underline {\left( {{\text{iii}}} \right)} \,$$ . The ferrous ions are further oxidised by atmospheric oxygen to ferric ions which come out as rust, $$\underline {\left( {{\text{iv}}} \right)} $$ and with further production of $$\underline {\left( {\text{v}} \right)} $$ ions.
| (i) | (ii) | (iii) | (iv) | (v) | |
|---|---|---|---|---|---|
| (a) | oxidation | anode | cathode | Fe2O3.xH2O | hydrogen |
| (b) | reduction | cathode | anode | Fe3O4 | hydroxide |
| (c) | oxidation | cathode | anode | Fe2O3.xH2O | hydrogen |
| (d) | oxidation | anode | cathode | Fe2O3.H2O | ferrous |
A
(a)
B
(b)
C
(c)
D
(d)
Answer :
(a)
198. $${E^ \circ }$$ for the cell, $$Zn\left| {Z{n^{2 + }}\left( {aq} \right)} \right|\left| {C{u^{2 + }}\left( {aq} \right)} \right|Cu$$ is $$1.10 V$$ at $${25^ \circ }C.$$ The equilibrium constant for the reaction,$$Zn\left( s \right) + C{u^{2 + }}\left( {aq} \right) \rightleftharpoons $$ $$Cu\left( s \right) + Z{n^{2 + }}\left( {aq} \right)$$ is of the order
A
$${10^{ - 37}}$$
B
$${10^{ - 28}}$$
C
$${10^{18}}$$
D
$${10^{17}}$$
Answer :
$${10^{ - 37}}$$
199.
Electrolysis of an aqueous solution of $$AgN{O_3}$$ with silver electrodes produces $$\underline {\left( {\text{i}} \right)} $$ at cathode while $$\underline {\left( {{\text{ii}}} \right)} $$ ions are dissolved from anode. When $$Pt$$ electrodes are used $$\underline {\left( {{\text{iii}}} \right)} $$ is produced at anode and $$\underline {\left( {{\text{iv}}} \right)} $$ at cathode.
| (i) | (ii) | (iii) | (iv) | |
|---|---|---|---|---|
| (a) | $${H_2}$$ | $$NO_3^ - $$ | $$O{H^ - }$$ | $${H_2}$$ |
| (b) | $$Ag$$ | $${H^ + }$$ | $${O_2}$$ | $${H_2}$$ |
| (c) | $$Ag$$ | $$A{g^ + }$$ | $${O_2}$$ | $$Ag$$ |
| (d) | $$Ag$$ | $${H^ + }$$ | $$A{g^ + }$$ | $${O_2}$$ |
A
(a)
B
(b)
C
(c)
D
(d)
Answer :
(c)
200.
Electrode potentials $$\left( {{E^ \circ }} \right)$$ are given below :
$$\eqalign{
& \frac{{C{u^ + }}}{{Cu}} = + 0.52\,V, \cr
& \frac{{F{e^{3 + }}}}{{F{e^{2 + }}}} = + 0.77\,V, \cr
& \frac{1}{2}\frac{{{I_2}\left( s \right)}}{{{I^ - }}} = + 0.54\,V, \cr
& \frac{{A{g^ + }}}{{Ag}} = + 0.88V. \cr} $$
Based on the above potentials, strongest oxidizing agent will be :
A
$$C{u^ + }$$
B
$$F{e^{3 + }}$$
C
$$A{g^ + }$$
D
$${I_2}$$
Answer :
$$A{g^ + }$$