Secondary Cells

Q.

Which of the following reactions occurs at the cathode of a common dry cell

[NCERT 1978]

1. 
   

2. 
   

3. 
   

4. 
   

Q. Now he tried his hands with a calculator. I think you know whats coming next! Which of these observations of Rancho were TRUE?

1. It consists of a cadmium electrode (as anode)
2. At anode:
   $Cd\left(s\right)+2O{H}^{-}\left(aq\right)\to d\left(OH{)}_2\right(s)+2e^{-}$
3. At cathode:
   $Ni{O}_2\left(s\right)+2H_{2}O+2e^{-}\to Ni\left(OH{)}_2\right(s)+2O{H}^{-}(aq)$
4. A metal grid containing nickel (IV) oxide acts as cathode

Q. Now Rancho got more curious and he wanted to check other batteries as well. So he tried his motorcycle battery this time. Again he made some observations. Which of the following are TRUE?

1. It consists of a lead anode
2. A grid of lead packed with lead dioxide $\left(Pb{O}_2\right)$ acts as cathode
3. It is non-rechargeable
4. A $38\%$ solution of sulphuric acid is used as an electrolyte

Q. Which of the following is TRUE in case of recharging a Lead Storage Battery?

1. $PbS{O}_4\left(s\right)+2e^{-}\to Pb\left(s\right)+S{O}_4^{2-}\left(aq\right)$
2. $PbS{O}_4\left(s\right)+2H_{2}O\to Pb{O}_2\left(s\right)+S{O}_4^{2-}\left(aq\right)+4H^{+}\left(aq\right)+2e^{-}$
3. $Pb\left(s\right)+S{O}_4^{2-}\left(aq\right)\to PbS{O}_4\left(s\right)+2e^{-}$
4. $Pb{O}_2\left(s\right)+S{O}_4^{2-}+4H^{+}\left(aq\right)+2e^{-}\to PbS{O}_4\left(s\right)+2H_{2}O\left(l\right)$

Q. The secondary cells are also called as storage cell or an accumulator since

1. Both $\left(C\right)$ and $\left(B\right)$
2. The products of the chemical reaction get accumulated
3. Same cell can be used for delivering/electrical energy over and over again
4. Same cell can be used for storing/electrical energy over and over again

Q. Match the following.

Q.

1. Both Assertion and Reason are true and Reason is the correct explanation of Assertion
2. Both Assertion and Reason are true but Reason is not the correct explanation of Assertion
3. Assertion is true but Reason is false
4. Assertion is false but Reason is true
5. Both Assertion and Reason are false

Q. Why does the cell potential of mercury cell remain constant throughout its life ?

Q.

Given :

Oxidation :

$H_2{O}_2\to O_2+2H^{\oplus }+2e^{-}$

$E^{\ominus }=-0.69V$;

$2F^{\ominus }\to F_2+2e^{-}$

$E^{\ominus }=-2.87V$;

Reduction :

$H_2{O}_2+2H^{\oplus }+2e^{-}\to 2H_{2}O$

$E^{\ominus }=-1.77V$;

$2I^{\ominus }\to I_2+2e^{-}$

$E^{\ominus }=-0.54V$;

Which of the following statements is/are correct ?

1. $H_2{O}_2$ behaves as an oxidant for $I^{\ominus }$.
2. $H_2{O}_2$ behaves as a reductant for $I_2$.
3. $H_2{O}_2$ behaves as an oxidant for $F^{\ominus }$.
4. $H_2{O}_2$ behaves as a reductant for $F_2$.

Q. Which one is not correct for e.m.f. of a galvanic cell?

1. $E_{cell}=E_{O{P}_{anode}}+E_{R{P}_{cathode}}$
2. $E_{cell}=E_{O{P}_{LHS}}+E_{R{P}_{RHS}}$
3. $E_{cell}=$ higher oxidation potential - lower oxidation potential
4. $E_{cell}=$ lower oxidation potential - higher oxidation potential