Magneesium sulphide
The compound name for Mg(NO3)2 is magnesium nitrate.
The compound is called magnesium hydroxide.
The compound with the formula Mg(NO2)2 is magnesium nitrite.
Magnesium dihydrogen arsenate is the name. The formula is Mg(H2AsO4)2
Magnesium Permanganate
This compound is magnesium acetate.
If this really is a compound, it is named "magnesium bromide hydroxide".
The name of this compound is magnesium bromide hydroxide.
The correct name for the ionic compound MgBr is magnesium bromide.
This is probable an error - the compound doesn't exist.
The name of the compound with this formula is "magnesium sulfide".
Mg which stands for Magnesium is the element to begin with, not a compound.