Why are atoms in a covalent bond usually a certain distance away from each other?

For general projectile motion, when the projectile is at the highest point of its trajectory, its acceleration is zero? a)the horizontal and vertical components of its velocity are zero. b) its velocity is perpendicular to the acceleration. c)the horizontal component of its velocity is zero. d)its velocity and acceleration are both zero.

Achlorine atom has 17 protons and 18 neutrons. what is its mass number? what is its atomic number?

Observations show that interstellar clouds can have almost any shape and