The color of acidified $K_2Cr_2O_7$ is not changed by:

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:

$2KMnO_4 \xrightarrow{200^{\circ}C} K_2MnO_4 + MnO_2 + O_2$. Here,'$X$' is $K_2MnO_4$. Which of the following statements is correct for '$X$'?

Which among the following statements is incorrect for manganate and permanganate ions?

In a borax bead test under hot condition,a metal salt is heated at point $B$ of the flame,resulting in a green-coloured salt bead. The spin-only magnetic moment value of the salt is $..........$ $BM$ (Nearest integer). [Given atomic number of $Cu=29, Ni=28, Mn=25, Fe=26$]

Which one of the following is known as lunar caustic when in fused state?