Electrochemistry MCQ Questions & Answers in Physical Chemistry | Chemistry
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261.
At $${25^ \circ }C$$ $$molar$$ conductance of $$0.1$$ $$molar$$ aqueous solution of ammonium hydroxide is $$9.54\,\,{\Omega ^{ - 1}}c{m^2}\,mo{l^{ - 1}}$$ and at infinite dilution its molar conductance is $$238\,\,{\Omega ^{ - 1}}\,c{m^2}\,mo{l^{ - 1}}.$$ The degree of ionisation of ammonium hydroxide at the same concentration and temperature is
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263.
Which of the following statements is correct?
A
$${E_{{\text{cell}}}}$$ and $${\Delta _r}G$$ of cell reaction both are extensive properties.
B
$${E_{{\text{cell}}}}$$ and $${\Delta _r}G$$ of cell reaction both are intensive properties.
C
$${E_{{\text{cell}}}}$$ is an intensive property while $${\Delta _r}G$$ of cell reaction is an extensive property.
D
$${E_{{\text{cell}}}}$$ is an extensive property while $${\Delta _r}G$$ of cell reaction is an intensive property.
Answer :
$${E_{{\text{cell}}}}$$ is an intensive property while $${\Delta _r}G$$ of cell reaction is an extensive property.
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264.
A standard hydrogen electrode has a zero potential because
A
hydrogen can be most easily oxidised
B
hydrogen has only one electron
C
the electrode potential is assumed to be zero
D
hydrogen is the lightest element
Answer :
the electrode potential is assumed to be zero
According to convention, the standard hydrogen electrode is assigned a zero potential at all temperatures.
265.
Saturated solution of $$KN{O_3}$$ is used to make ‘salt—bridge' because
A
Velocity of $${K^ + }$$ is greater than that of $$NO_3^ - $$
B
velocity of $$NO_3^ - $$ is greater than that of $${K^ + }$$
C
velocities of both $${K^ + }$$ and $$NO_3^ - $$ are nearly the same
D
$$KN{O_3}$$ is highly soluble in water
Answer :
velocities of both $${K^ + }$$ and $$NO_3^ - $$ are nearly the same
The salt used to make ‘salt—bridge’ must be such that the ionic mobility of cation and anion are of comparable order so that they can keep the anode and cathode half cells neutral at all times. $$KN{O_3}$$ is used because velocities of $${K^ + }$$ and $$NO_3^ - $$ ions are nearly same
266.
In a Daniell cell,
A
the chemical energy liberated during the redox reaction is converted to electrical energy
B
the electrical energy of the cell is converted to chemical energy
C
the energy of the cell is utilised in conduction of the redox reaction
D
the potential energy of the cell is converted into electrical energy.
Answer :
the chemical energy liberated during the redox reaction is converted to electrical energy
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267.
In a hydrogen-oxygen fuel cell, combustion of hydrogen occurs to
A
produce high purity water
B
create potential difference between two electrodes
C
generate heat
D
remove adsorbed oxygen from elctrode surfaces
Answer :
create potential difference between two electrodes
In $${H_2} - {O_2}$$ fuel cell, the combustion of $${H_2}$$ occurs to create potential difference between the two electrodes
268.
In electrolytic reduction of a nitroarene with $$50\% $$ current efficiency $$20.50\,g$$ of the compound is reduced by $$2 \times 96500\,C$$ of electric charge. The molar mass of the compound is
269.
An electric current is passed through silver nitrate solution using silver electrodes. $$15.28\,g$$ of silver was found to be deposited on cathode. What will be
the weight of copper deposited on cathode if same amount of electricity is passed through copper sulphate solution using copper electrodes?
A
4.49 $$g$$
B
6.4 $$g$$
C
12.8 $$g$$
D
3.2 $$g$$
Answer :
4.49 $$g$$
Equivalent $$wt.$$ of $$Ag = \frac{{108}}{1} = 108$$
Equivalent $$wt.$$ of $$Cu = \frac{{63.5}}{2} = 31.75$$
$$\frac{{{\text{Eq}}.\,wt\,{\text{of}}\,\,Ag}}{{{\text{Eq}}.\,wt.\,{\text{of}}\,\,Cu}}$$ $$ = \frac{{{\text{Mass of }}Ag{\text{ deposited}}}}{{{\text{Mass of }}Cu{\text{ deposited}}}}$$
$$\frac{{108}}{{31.75}} = \frac{{15.28}}{W} \Rightarrow W$$ $$ = \frac{{15.28 \times 31.75}}{{108}} = 4.49\,g$$
270.
Electrical conductance through metals is called metallic or electronic conductance and is due to the movement of electrons. The electronic conductance depends on
A
the nature and structure of the metal
B
the number of valence electrons per atom
C
change in temperature
D
all of these
Answer :
all of these
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