Question

Acid

A compound that increases the hydroxide ions (OH-) when it is dissolved in a solution
Base

A compound that increases hydrogen ions (H+) when it is dissolved in a solution
Ions

An atom or molecule that has a positive or negative charge
pH

A value from 0 to 14 that is used to specify how acidic or basic a compound is when it is dissolved in water

Answer 1

Quick corrections and clearer definitions:

- Acid — A compound that increases the concentration of hydrogen ions (H+) when dissolved in water (or more precisely, donates H+). Example: HCl → H+ + Cl−. (In water H+ is more correctly present as H3O+, the hydronium ion.)

- Base — A compound that increases the concentration of hydroxide ions (OH−) when dissolved in water (or more generally, accepts H+). Example: NaOH → Na+ + OH−.

- Ion — An atom or molecule that carries a net electrical charge (positive = cation, negative = anion).

- pH — A numeric scale (typically ~0 to 14 for aqueous solutions at 25 °C) that measures acidity: pH = −log10[H+]. Low pH = acidic (more H+), high pH = basic (more OH−). At 25 °C pH + pOH = 14.

If you want, I can give a short mnemonic, list common strong acids/bases, or show how to calculate pH from concentration.