Oxygen is absorbed by molten $Ag$,which is evolved on cooling and the silver particles are scattered,this phenomenon is known as

Which of the following oxidation states of manganese exhibits the most powerful oxidizing property?

Assertion : $PbI_4, BiCl_5, FeI_3, CuI_2$ do not exist. Reason : Higher oxidation states of metal ions are strong oxidising agents which give redox reactions with the iodide ion.

For $Cr, Mn, Fe,$ and $Co$,the $E^{0}_{M^{3+}/M^{2+}}$ values are $-0.41, +1.57, +0.77,$ and $+1.97 \ V$ respectively. For which metal is the change in oxidation state from $+2$ to $+3$ the easiest?

How would you account for the following:
$(i)$ Of the $d^{4}$ species,$Cr^{2+}$ is strongly reducing while $Mn^{3+}$ is strongly oxidising.
$(ii)$ $Co^{2+}$ is stable in aqueous solution but in the presence of complexing reagents it is easily oxidised.
$(iii)$ The $d^{1}$ configuration is very unstable in ions.

Explain the catalytic properties of transition metals.