How many sigma and how many pi bonds are present in the ethene molecule (c2h4)?
a. 4 sigma and 1 pi
b. 4 sigma and 2 pi
c. 5 sigma and 2 pi
d. 5 sigma and 1 pi

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).