Which chemical equation is balanced?

a.
2pcl5 + 2h2o → 2hcl + h3po4

b.
pcl5 + h2o → hcl + h3po4

c.
pcl5 + 3h2o → 5hcl + h3po4

d.
pcl5 + 4h2o → 5hcl + h3po4

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).