$\mathrm{Mn}_2 \mathrm{O}_3$, Brown

$\mathrm{MnO}_2$, Black

$\mathrm{KMnO}_4$, Purple

$\mathrm{K}_2 \mathrm{MnO}_4$, Dark green

Vanadium( $\mathrm{Z}=23$ )

Manganese ( $\mathrm{Z}=25$ )

Iron ( $\mathrm{Z}=26$ )

Chromium ( $\mathrm{Z}=24$ )

$T i< V< C r< M n$ [Increasing order of melting point]

$\mathrm{Ti}^{3+}<\mathrm{V}^{3+}<\mathrm{Cr}^{3+}<\mathrm{Mn}^{3+}$ [Increasing order of magnetic moment]

$T i< V< M n< C r$ [Increasing order of second ionisation enthalpy]

$T i< V< C r< M n$ [Increasing order of highest oxidation state]

A is false but R is true

Both $A$ and $R$ are true but $R$ is the correct explanation of $A$

$A$ is true but $R$ is false

Both $A$ and $R$ are true, $R$ is not the correct explanation of $A$