EMF

Q. Calculate the emf of the following cell at $298\text{K}$.
$Zn\left(s\right)\mid Z{n}^{2+}(aq,0.1M)\parallel A{g}^{+}(aq,0.01M)\mid Ag\left(s\right)$
Given:
$E_{Z{n}^{2+}/Zn}^0=-0.76V$
$E_{A{g}^{+}/Ag}^0=+0.80V$

1. $E_{cell}=1.472V$
2. $E_{cell}=-1.472V$
3. $E_{cell}=+1.732V$
4. $E_{cell}=-1.732V$

Q.

What are Personal Error, Instrumental Error, and Random Error? Explain by giving an example?

Q. What is the direction of flow of electrons in an electrolytic cell?

1. Anode to cathode externally
2. Anode to cathode internally
3. Cathode to anode externally
4. Cathode to anode in the solution

Q.

A common emitter amplifier has a voltage gain of $50$, an input impedance of $100\Omega$ and an output impedance of $200\Omega$. The power gain of the amplifier is

1. $500$

2. $1000$

3. $1250$

4. $50$

Q. Which of the following factor(s) affect the electrode potential?

1. Composition of the reaction mixtures
2. Concentration of ions in the half cells
3. Temperature
4. All of the above.

Q.

For spontaneous reaction, the $\Delta G$, equilibrium constant (k) and $E^0$ cell are respectively.

1. -ve, <1, -ve

2. +ve, >1, -ve

3. -ve, >1, +ve

4. -ve, >1, -ve

Q. What is the significance of 3+ in [Co(CN)₆]³⁺ ? How does it affect the oxidation state of Cobalt ?

Q.

Why is direct current used in electrolysis?

Q.

Arrange Na, Ca, K, Mg in the descending order of their reactivity.

Q. Which of the following represents the cathode half cell reaction of a Daniel cell?

1. $Cu\left(s\right)\to C{u}^{2+}\left(aq\right)+2e^{-}$
2. $Z{n}^{2+}\left(aq\right)+2e^{-}\to Zn\left(s\right)$
3. $Zn\left(s\right)\to Z{n}^{2+}\left(aq\right)+2e^{-}$
4. $C{u}^{2+}\left(aq\right)+2e^{-}\to Cu\left(s\right)$

Q. In the cell Pt(s)\vert H_2(g, 1bar)\vert HCl(aq)\vert AgCl(s)\vert Ag(s)\vert Pt(s) the cell potential is 0.92 when a 10^{-6}molal HCl solution is used. The s†an dard electrode potential of (AgCl/Ag, Cl –) electrode is : (1) 0.20 V (2) 0.76 V (3) 0.40 V (4) 0.94 V ?

Q. Calculate the emf of the following cell at ${25}^{\circ }C$ : $Ag\left(s\right)|A{g}^{+}\left({10}^{-3}M\right)||C{u}^{2+}\left({10}^{-1}M\right)|Cu\left(s\right)$
Given $E_{cell}^{\circ }=+0.46V$ and $log{10}^n=n.$

Q. 19.Electrode potential for the following half cell reactions are Zn=Zn^+2+2e;E^°=+0.75VFe=Fe^+2+2e;E^°=+0.44V The EMF for the cell reaction Fe^+2+Zn=Zn^+2+Fe will be

Q. $E^{\circ }$ for the reaction $Fe+Z{n}^{2+}\to Zn+F{e}^{2+}$ is -0.35 V. The given reaction is:

1. Feasible
2. Not feasible
3. In equilibrium
4. None

Q. 25. Two concentration cells of Ag with Ag electrode in AgNO3.In first cell, concentration of one electrode is `1M and other electrode is .1M and emf is .06V.In second cell concentration of one elecrode 1M and other electrode is .01 M.Calculate the emf of the second cell C_Total energy. D_intermolecular force s

Q.

Positive electrode is called the ________.

Q. Find the emf of the given cell.$Ni\left(s\right)|N{i}^{2+}(aq,1.0M)||A{u}^{3+}(aq,0.1M)|Au\left(s\right)$
$[E^0\text{for}N{i}^{2+}/Ni=-0.25V$
$E^0\text{for}A{u}^{3+}/Au=1.50V]$

1. $1.25V$
2. $-0.96V$
3. $2.31V$
4. $1.73V$

Q. Calculate emf of the following cell at ${25}^{\circ }C$:
$Sn|S{n}^{2+}\left(0.001M\right)||H^{+}\left(0.01M\right)|H_2$ (g)(1 bar)|Pt(s)
$E_{S{n}^{2+}/Sn}^0=-0.14V{E}_{H+/H_2}^0=0.00V$

Q.

A change of $8mA$ in the emitter current brings a change of $7.9mA$ in collector current. How much change in base current is required to have the same change of $7.9mA$ in collector current? Find values of $\alpha$ and $\beta$.

Q. 22. By how which will potential of zinc electrode change if solution of znso4 in which it is diluted to 10times at 298k A_decreases by 30ml. B_increases by 30mV C_increases by 60mV. D_decreases by 60mV

Q. How long has a current of 3 ampere to be supplied through a solution of silver nitrate to coat a metal surface of $80c{m}^2$ with $0.005mm$ thick layer?
Density of silver is $10.5gc{m}^{-3}$

1. $303s$
2. $67s$
3. $180s$
4. $125s$

Q.

A more reactive metal displaces a less reactive metal from the aqueous solution. From the following set tell which one represents a correct picture, of both the possible ($\mathbf{Y}$) reaction and impossible ($\mathbf{N}$) reactions between metals and the solution of different salts.

1. Metal	${\mathrm{Al}}_2{\left({\mathrm{SO}}_4\right)}_2$	${\mathrm{CuSO}}_4$	${\mathrm{FeSO}}_4$	${\mathrm{ZnSO}}_4$
   $\mathrm{Al}$	$\mathbf{N}$	$\mathbf{Y}$	$\mathbf{Y}$	$\mathbf{Y}$

2. Metal	${\mathrm{Al}}_2{\left({\mathrm{SO}}_4\right)}_2$	${\mathrm{CuSO}}_4$	${\mathrm{FeSO}}_4$	${\mathrm{ZnSO}}_4$
   $\mathrm{Cu}$	$\mathbf{Y}$	$\mathbf{N}$	$\mathbf{N}$	$\mathbf{N}$

3. Metal	${\mathrm{Al}}_2{\left({\mathrm{SO}}_4\right)}_2$	${\mathrm{CuSO}}_4$	${\mathrm{FeSO}}_4$	${\mathrm{ZnSO}}_4$
   $\mathrm{Fe}$	$\mathbf{Y}$	$\mathbf{Y}$	$\mathbf{N}$	$\mathbf{N}$

4. Metal	${\mathrm{Al}}_2{\left({\mathrm{SO}}_4\right)}_2$	${\mathrm{CuSO}}_4$	${\mathrm{FeSO}}_4$	${\mathrm{ZnSO}}_4$
   $\mathrm{Zn}$	$\mathbf{N}$	$\mathbf{Y}$	$\mathbf{N}$	$\mathbf{Y}$

Q. Two electrochemical cells are assembled in which the following reactions occur.

$V^{2+}\left(aq\right)+V{O}^{2+}\left(aq\right)+2H^{+}\left(aq\right)\to 2V^{3+}\left(aq\right)+H_{2}O\left(l\right);E_{cell}^0=0.616V$


$V^{3+}\left(aq\right)+A{g}^{+}\left(aq\right)+H_{2}O\left(l\right)\to V{O}^{2+}\left(aq\right)+2H^{+}\left(aq\right)+Ag\left(s\right);E_{cell}^0=0.439V$

Calculate the $E^0$ for the half-cell reaction,
$V^{3+}\left(aq\right)+e\to V^{2+}\left(aq\right)$
Given :
$(E_{A{g}^{+}\left(aq\right)/Ag\left(s\right)}^0=0.799V)$

1. $-1.055V$
2. $+1.055V$
3. $-0.563V$
4. $-0.256V$

Q. Which of the following statement is incorrect about electrochemical cell?

1. Electrons are released at anode
2. Chemical energy is converted into electrical energy
3. Salt bridge maintains the electrical neutrality of the electrolytes
4. Cell can work indefinitely

Q. Write the cathode and anode reaction of i. Voltaic cell ii. Nickel-Cadmium cel

Q. Which of the following is a unit of electrode potential?

1. Coloumb
2. Ampere
3. Volt
4. $mol{L}^{-1}$

Q. On the basis of standard electrode potential of redox couples given below, find out which of the following is the strongest oxidising agent.
$(E^0\text{values}:F{e}^{3+}\mid F{e}^{2+}=+0.77V;I_2(s)\mid I^{-}=+0.54V;C{u}^{2+}|Cu=+0.34V;A{g}^{+}\mid Ag=+0.80V)$

1. $I_2\left(s\right)$
2. $F{e}^{3+}$
3. $A{g}^{+}$
4. $C{u}^{2+}$

Q. Electromotive force (EMF) of a cell is

1. The potential required to oxidize one mole of ions.
2. The potential difference between electrode and electrolyte in a cell.
3. The difference between the reduction potential of cathode and anode.
4. None of the above.

Q.

How would you change ${\mathrm{Cu}}^{2+}$ ion to $\mathrm{Cu}$?

Q.

The electrode connected to the negative terminal of the voltage source is called

1. Cathode

2. Anode

3. Diode

4. Cathode ray