On heating $KMnO_4$,one among the following is not formed:

Which one of the following is an amphoteric oxide?

Which mineral among the following contains Vanadium in it?

Which lanthanoid compound is used in pigments?

$K_2Cr_2O_7 + H_2O_2 \xrightarrow{H^{+}} $

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 $Cu=29, Ni=28, Mn=25, Fe=26$]