Redox Reactions...

Oxidation number of $$Cr$$ in the following complex is:

For the half reaction
$$B(s) \rightarrow B^{2+} + 2e^{-}$$         $$E_{1}^{\circ} = - 0.44 V$$
and  $$B_{2}+\rightarrow B^{3+} + e^{-}$$    $$E_{2}^{\circ} = 1.3 V$$
What is $$E^{\circ}$$ for the reaction,
$$3e^{-} + B^{+3} \rightarrow B(s)$$

The oxidation number of S is $$(CH_{3})_{2}SO$$ is ?

The oxidation number of S in $$(CH_{3})_{2}SO$$ is ?

The standard electrode potential of the half cells is given below:
$$Zn^{2+}+2e^{-}\rightarrow Zn; E=-0.76 V$$
$$Fe^{2+}+2e^{-}\rightarrow Fe; E=-0.44 V$$
The emf of the cell $$Fe^{2+}=Zn^{-}\rightarrow Zn^{2+}+Fe $$

Highest positive oxidation state shown by:

The lowest oxidation state shown by an element in its compound is ?

The elements having lowest and highest oxidation number respectively are:

The conversion of 2,3-dibromobutane to 2-butene with $$Zn$$ is:

Oxidation numbers of P in $$P{ O }_{ 4 }^{ 3- }$$, of S in $$S{ O }_{ 4 }^{ 2- }$$ and that of Cr in $$C{ r }_{ 2 }{ O }_{ 7 }^{ 2- }$$ are respectively: