Ldentify the atom whose nucleus is
composed of 56 protons and 82
neutrons.

Barium-138

Explanation:

The mass number is the atomic number + the number of neutrons. ... Identify the atom whose nucleus is composed of 56 protons and 82 neutrons. Barium-138 (the number of protons identifies the atom) Gallium has two naturally occurring isotopes: Ga-69 with a mass of 68.9256 amu and a natural abundance of 60.11% and Ga-71.

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).