Because it is made up of one type of element only. Thus it is an element, not a mixture.
Neither. Magnesium is an element.
Yes it is a mixture of magnesium hydroxide and water.
No, magnesium is an element and therefore a pure substance.
Mixture of sodium carbonate and magnesium
Magnesium hydride is a compound.
Dolomite limestone is a mixture of calcium carbonate and magnesium carbonate.
Element.
No, it is a compound, not a mixture. Its formula is MgO, and it contains Magnesium and Oxygen (two fairly common elements).
it is an element as it contains same kind of atoms
Neither. It's an element.
Compound
One way would be to wash the mixture with water, which will react with magnesium oxide to form magnesium hydroxide and then dissolve the latter. The carbon will remain behind as a solid.