Asap which of the following are examples of chemical changes -silver tarnishes - a sheet of copper is pounded into the shape of a bowl - barium melts at 725° c - hydrogen reacts with oxygen to form water

 Hydrogen reacts with oxygen to form water

Explanation:   Chemical changes are those which changes the identity of the chemical nature of any substance.

Thus out of the given options , the correct one is the formation of the water molecule when hydrogen reacts with oxygen as it is changing the identity of hydrogen and oxygen atoms to form a molecule of water.

The rest of the three options belongs to the category of the physical changes in which the chemical nature of any substance has not been changed but only the properties which an be easily observed can be changed.

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).

where are the choice options?