Find the value of spin-only magnetic moment for chromium cation in $+2$ state. (in $BM$)

$Mn^{2+}$ compounds are more stable than $Fe^{2+}$ compounds towards oxidation to their $+3$ state,because

Given below are two statements:
Statement $I$: $Cr^{2+}$ is oxidising and $Mn^{3+}$ is reducing in nature.
Statement $II$: $Sc^{3+}$ compounds are repelled by the applied magnetic field.
In the light of the above statements,choose the most appropriate answer from the options given below:

Which of the following ions is coloured?

Which of the following statements about the interstitial compounds is incorrect?

Which of the following sets of elements does not belong to the transition elements set?