The color of $KMnO_4$ is due to:

$CoO \cdot Al_2O_3$ is called

Given below are some statements about $Mn$ and $Mn_2O_7$. Identify the correct statements:
$A$. $Mn$ forms the oxide $Mn_2O_7$ in which $Mn$ is in its highest oxidation state.
$B$. Oxygen stabilizes the $Mn$ in higher oxidation states by forming multiple bonds with $Mn$.
$C$. $Mn_2O_7$ is an ionic oxide.
$D$. The structure of $Mn_2O_7$ consists of one bridged oxygen.
Choose the correct answer from the options given below:

Which of the following statements is incorrect?

Name the oxometal anions of the first series of the transition metals in which the metal exhibits the oxidation state equal to its group number.

Which transition metal oxide among the following has electrical conductivity similar to that of copper?