What is the decreasing order of deposition of metal on electrode if standard reduction potentials are given as: $Ag^{+} | Ag = 0.80 \ V$,$Cu^{2+} | Cu = 0.337 \ V$,$Sn^{2+} | Sn = -0.136 \ V$,$Cd^{2+} | Cd = -0.403 \ V$?

The standard electrode potentials of two half-cells are given as: $Ni^{2+}_{(aq)} + 2e^{-} \rightarrow Ni_{(s)}$; $E^o = -0.25 \ V$ and $Zn^{2+}_{(aq)} + 2e^{-} \rightarrow Zn_{(s)}$; $E^o = -0.76 \ V$. What is the standard $emf$ of the cell formed by connecting these two half-cells in $volt$?

The standard electrode potentials of the half-cells are given below:
$Zn^{2+} + 2e^- \to Zn$; $E^{\circ} = -0.76 \, V$
$Fe^{2+} + 2e^- \to Fe$; $E^{\circ} = -0.44 \, V$
The $EMF$ of the cell $Fe^{2+} + Zn \to Zn^{2+} + Fe$ is ............ $V$.

Given are $E^{\circ}$ values for some half reactions:
$I_2 + 2e^{-} \to 2I^{-}$ ; $E^{\circ} = 0.54 \, V$
$MnO_4^{-} + 8H^{+} + 5e^{-} \to Mn^{2+} + 4H_2O$ ; $E^{\circ} = 1.52 \, V$
$Fe^{3+} + e^{-} \to Fe^{2+}$ ; $E^{\circ} = 0.77 \, V$
$Sn^{4+} + 2e^{-} \to Sn^{2+}$ ; $E^{\circ} = 0.1 \, V$
The strongest reducant and oxidant respectively are:

The $emf$ of a galvanic cell constituted with the electrodes $Zn^{2+} | Zn$ $(-0.76 \ V)$ and $Fe^{2+} | Fe$ $(-0.41 \ V)$ is

What is denoted by a negative $E^o$ and a positive $E^o$ value in electrochemistry?