Because on both of them you are typing/writing something.
Answer:
The correct answer is D
Explanation:
Many substances hold their molecules together in the liquid or solid bosom. This is due, in addition to the pressure and temperature conditions, by the forces of Van der Waals. These are still produced in nonpolar molecules by the movement of electrons through the molecules; in extremely short periods of time, their electrons "charge" towards one end of the molecule, producing small dipoles and keeping the molecules very close to each other.
An ionic compound consists of a metal AND a non-metal.
<em>Option A:</em>
Oxygen and fluorine are non-metals.
<em>Option B:</em>
Sodium and aluminium are non-metals.
<em>Option C:</em>
Calcium is a metal and chlorine is a non-metal.
<em>Option D:</em>
Nitrogen and sulfur are non-metals.
Thus, the answer is C.
<span>The answer is A because an elements only consists of one type of atom. Example. the element H (hydrogen) only contains 1 hydrogen atom. I hope this helps!! </span>