Which of the following is the heaviest metal?

For $M^{2+} / M$ and $M^{3+} / M^{2+}$ systems,the ${E^{\Theta}}$ values for some metals are as follows:
$Cr^{2+} / Cr : -0.9 \ V$
$Cr^{3+} / Cr^{2+} : -0.4 \ V$
$Mn^{2+} / Mn : -1.2 \ V$
$Mn^{3+} / Mn^{2+} : +1.5 \ V$
$Fe^{2+} / Fe : -0.4 \ V$
$Fe^{3+} / Fe^{2+} : +0.8 \ V$
Use this data to comment upon:
$(i)$ The stability of $Fe^{3+}$ in acid solution as compared to that of $Cr^{3+}$ or $Mn^{3+}$ and
$(ii)$ The ease with which iron can be oxidised as compared to a similar process for either chromium or manganese metal.

Which of the following elements are not regarded as transition elements?

Which of the following pairs of elements in their respective oxidation states develops the same value of calculated spin-only magnetic moment?

The magnetic moment of a metal ion of the first transition series is $2.83 \ BM$. Therefore,it will have how many unpaired electrons?

Observe the following ions: $V^{2+}, Zn^{2+}, Cu^{2+}, Fe^{2+}, Fe^{3+}, Ti^{3+}, Sc^{3+}, Ti^{4+}, Ni^{3+}, Co^{3+}, Cu^+$. How many ions in the above list have zero magnetic moment?