Question

which of the following is a compound?
a sodium chloride
b hydrogen gas
c oxygen gas
d lithium
e chlorine gas

Explanation:

A compound is a substance made up of two or more different elements chemically combined. Sodium chloride (NaCl) is composed of sodium (Na) and chlorine (Cl) elements. Hydrogen gas ($H_2$), oxygen gas ($O_2$), lithium (Li), and chlorine gas ($Cl_2$) are all elements or elemental substances, not compounds.

Answer:

A. sodium chloride