Which of the following statements is $NOT$ correct for $H_2-O_2$ fuel cell?

$A$ concentrated solution of lead nitrate in water can be stored in

Given the standard electrode potentials $E^{0}_{Fe^{2+}|Fe} = -0.44 \, V$ and $E^{0}_{Fe^{3+}|Fe^{2+}} = 0.77 \, V$. If $Fe^{2+}$,$Fe^{3+}$,and $Fe$ are all present together,then:

Which of the following statements are correct regarding a fuel cell that uses hydrogen and oxygen as fuels?
$A$. It has been used in spaceships.
$B$. It has an efficiency of about $40 \%$ to $60 \%$ to produce electricity.
$C$. It uses aluminium as a catalyst.
$D$. It is eco-friendly.
$E$. It is actually a type of galvanic cell.

Which substance is used as cathode in a mercury cell?

For the Galvanic cell:
$Ag_{(s)} \, | \, Ag_2C_2O_{4(s)} \, | \, C_2O_4^{2-} (0.02 \ M) \, || \, Ag^{+}(0.5 \ M) \, | \, Ag_{(s)}$
$EMF$ of the cell is $0.264 \ V$ at $25 \ ^oC$. The $K_{sp}$ of $Ag_2C_2O_{4(s)}$ is:
$[Given: \frac{2.303RT}{F} = 0.06, \ \log 2 = 0.3]$