In the first transition series,the highest $B.P.$ and $M.P.$ is of

Which of the following pairs of ions are colourless?

Given below are two statements: one is labelled as Assertion $(A)$ and the other is labelled as Reason $(R)$. Assertion $(A)$: In aqueous solutions $Cr^{2+}$ is reducing while $Mn^{3+}$ is oxidising in nature.
Reason $(R)$: Extra stability to half-filled electronic configuration is observed than incompletely filled electronic configuration.
In the light of the above statement,choose the most appropriate answer from the options given below:

Which of the following has the maximum number of unpaired electrons?

Given below are two statements:
Statement $I :$ The $E^{\circ}$ value of $Ce^{4+} / Ce^{3+}$ is $+1.74 \, V$.
Statement $II :$ $Ce$ is more stable in $Ce^{4+}$ state than $Ce^{3+}$ state.
In the light of the above statements,choose the most appropriate answer from the options given below:

Pairs of elements with the same number of electrons in their respective $4f$ orbital are [Atomic number: $Eu-63, Gd-64, Dy-66, Ho-67, Tm-69, Yb-70, Lu-71, Hf-72$]. Choose the correct answer from the options given below: