13. a. what is a salt?
b. give two examples of salts.

Explanation:

Salt:

It is solid chemical compound consist of cation and anion.

Examples:

Sodium chloride:

Sodium chloride is salt made up of chlorine and sodium. Sodium is present in the form of cation while chlorine is present in the form of anion. The charge on sodium is +1 while the charge on chlorine is -1. Sodium atom loses its one valance electrons which is accepted by chlorine and form ionic compound which is called sodium chloride.

Potassium bromide: KBr

Potassium bromide is salt which is formed when potassium lose its one electron to bromine atom. Electrostatic forces develop between them.

Through acid base reaction:

When acid and base react they form salt and water. The H⁺ of acid combine with OH⁻ of base and form water while anion of acid combine with cation of base and form salt.

HCl + NaOH →  NaCl   + H₂O

NaCl is salt which is produced by the HCl acid and sodium hydroxide base.

answer: c.

explanation:

there is none because earth is stationary and flat.