If 25 grams of aluminum react with 5grams of oxygen, how many grams of aluminum oxide are produced?

Se producirían 30 gramos de óxido de aluminio

Explicación: Ya que  en una reacción química no puede descubrirse ningún cambio en masa total de las substancias que en ella intervienen, pues en una reacción química ni se gana ni se pierde masa.  

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).