manganese (IV) oxide +4
Work Step by Step
$MnO_2$ $Mn$ is manganese. $O$ is oxygen, which his called oxide when naming compounds. Oxygen has a charge of -2. The compound is neutral, so the charge/oxidation number of the manganese element was +4 (-2*2 because there are 2 oxygen atoms in the compound). The name is written as element(oxidation number) element so $MnO$ is manganese (IV) oxide.