To overcome an energy barrier between reactants and products in a chemical reaction, energy must be provided to get the reaction started. this energy, which is recovered as the reaction proceeds, is called:

a c d and f

just finished the assignment

answer; talc and gypsum;

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).

it is the most commonly accepted one