The set of correct statements is:
$(i)$ Manganese exhibits $+7$ oxidation state in its oxide.
$(ii)$ Ruthenium and Osmium exhibit $+8$ oxidation state in their oxides.
$(iii)$ $Sc$ shows $+4$ oxidation state which is oxidizing in nature.
$(iv)$ $Cr$ shows oxidizing nature in $+6$ oxidation state.

Which of the following statements are correct?
$A$. The $M^{3+}/M^{2+}$ reduction potential for iron is greater than manganese.
$B$. The higher oxidation states of first row $d$-block elements get stabilized by oxide ion.
$C$. Aqueous solution of $Cr^{2+}$ can liberate hydrogen from dilute acid.
$D$. Magnetic moment of $V^{2+}$ is observed between $4.4-5.2 \ BM$.
Choose the correct answer from the options given below:

Which of the following will act as the best oxidizing agent?

For the four successive transition elements $(Cr, Mn, Fe, \text{ and } Co)$,the stability of $+2$ oxidation state will be in which of the following order?
(Atomic numbers: $Cr = 24, Mn = 25, Fe = 26, Co = 27$)

Which of the following are basic oxides among $Mn_2O_7 (I)$,$V_2O_3 (II)$,$V_2O_5 (III)$,$CrO (IV)$,and $Cr_2O_3 (V)$?

The correct order of basicity of oxides of vanadium is