$A$ metal $M$ has the electronic configuration $M: 1s^2 2s^2 2p^6 3s^2 3p^6 3d^{10} 4s^1$. To which block does this metal belong?

Given below are two statements: one is labelled as Assertion $A$ and the other is labelled as Reason $R$.
Assertion $A$: In $T \ell I_{3}$,isomorphous to $CsI_{3}$,the metal is present in $+1$ oxidation state.
Reason $R$: $T \ell$ metal has fourteen $f$ electrons in the electronic configuration.
In the light of the above statements,choose the most appropriate answer from the options given below:

Which of the following is not a characteristic of transition elements?

Among the following options,identify the element which exhibits the greatest number of oxidation states.

The $E^{\circ}$ value for the $Mn^{3+} / Mn^{2+}$ couple is more positive than that of $Cr^{3+} / Cr^{2+}$ or $Fe^{3+} / Fe^{2+}$ due to change of

The percentage $(\%)$ of iron in Mischmetal is ........ .