Which of the following compounds has the most acidic proton

Explanation:

The functional groups that show −I effect increase the acidity of the compound. Fluorine F shows maximum −I inductive effect among halogens. Therefore F substituted alcohol is more acidic than I substituted. The effectiveness of substituted F increases with the decrease in distance from hydroxylic proton. Therefore option D is the most acidic where F is adjacent to hydroxylic proton.

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).