Why is sodium more reactive than magnesium

Mg has two valence electrons  

Explanation:

Na has only one valence electron, so it readily donates that electron to other atoms to achieve an octet.

Mg must lose two valence electrons to get an octet. It takes extra energy to remove the second electron. In addition, the two electrons are in a filled s subshell, which has added stability.

the answer is c i believe

answer is: naturally occurring solid, inorganic compound or element is mineral.

minerals usually have crystalline form, that means than crystal constituents (atoms, molecules or ions) are arranged in a highly ordered microscopic structure, forming a crystal lattice that extends in all directions.

for example magnetite is a mineral of iron oxide (fe₂o₃).

calcite is a carbonate mineral and the most stable polymorph of calcium carbonate (caco₃).

dolomite is an   carbonate mineral composed of calcium magnesium carbonate (camg(co₃)₂).