Water and hydrogen peroxide are both composed of atoms of hydrogen and oxygen. the differences lie in the arrangement of the atoms.

a. behavioral
b. composed
c. macroscopic
d. submicroscopic

Submicroscopic

Explanation:

The differences lie in the submicroscopic arrangement of the atoms.i

Its chemical behavior that is the major difference between hydrogen peroxide and water. The single bond between the two atoms is weak, so that H2O2 is easily broken into H, HO2, or two OHs. The resulting molecules are free radicals, which makes H2O2 a potent oxidizing agent, and are therefore very reactive. This is why the chemical used to oxidize hydrazine fuel is used as a propelent for rocket propulsion, releasing hot gasses  that drive the missile.

the density(ratio between mass and volume as m/v) decreases from top to bottom in periodic table group as the size increases and nuclear charge decreases. but in periods density increases from left to right as atom size decreases and nuclear charge increases.