c. sodium a. c. salt a. 1. Which of the following is a compound? Sodium chloride b. magnesium 2. Which of the following substances is NOT a compound? Hydrogen peroxide b. sodium 3. Which of the following is the property of an element? It is the simplest substance b. It can be broken down into other types of substance It can be separated by physical means d. It can be decomposed into other substances a. C.​