If a substance has a pH of 4, is it acidic or basic. What type of ion is it going to give off when dissolved in water? Solution If a substance has a pH of 4, it is acidic in nature. An acid donates hydrogen ions. So,when this acid is dissolved in water (H2O), the balance between hydrogen ions and hydroxide ions is shifted. There will be more hydrogen ions rather than hydroxide ions in the solution. This kind of solution is called acidic solution. H2O -----------------> H+ + OH- Note: If, pH < 7 = Acidic in nature pH = 7 = Neutral solutions pH > 7 = Basic / Alkaline in nature.