Which statement about gases is true?
they are made up of particles that always move very slowly.
they are made up of particles that travel in a curved path when in motion.
they are made up of hard spheres that vibrate quickly in stationary positions.
they are made up of hard spheres that are in random motion.

They are made up of hard spheres that are in random motions.

They are made up of hard spheres that are in random motion.

Explanation:

Solid state : In this state, the molecules are present as hard spheres. They are arranged in regular and repeating pattern. The molecules are closely packed that means they are fixed and vibrate in place but they can not move from one place to another.

Liquid state : In this state, the molecules are present as hard spheres. They are present in random and irregular pattern. The molecules are closely packed but they vibrate in stationary positions.

Gaseous state : In this state, the molecules are present as hard spheres and in irregular pattern. The molecules are not closely packed and they can move freely from one place to another and spread out.

the number of valence electrons for each molecule or ion is shown beneath the structure. remember hydrogen will not have more than two electrons. this hydrogen is part of a covalent bond (sharing two electrons). a double bond here would cause hydrogen to share four electrons with phosphorus.