CBSE Class 10 Science 2019 · Paper 31/3/1 · Question 6

Effect of the concentration of ${\text{H}}^{+}(\text{aq})$ ions: It decides the nature of the solution. The greater the concentration of ${\text{H}}^{+}(\text{aq})$ ions, the more acidic the solution and the lower its pH. As the concentration of ${\text{H}}^{+}(\text{aq})$ ions decreases, the solution becomes less acidic, then neutral (pH $7$) and then basic (pH above $7$). Do basic solutions have ${\text{H}}^{+}(\text{aq})$ ions? Yes. Basic solutions also contain ${\text{H}}^{+}(\text{aq})$ ions, since water itself always gives some ${\text{H}}^{+}(\text{aq})$ and ${\text{OH}}^{-}(\text{aq})$ ions. Why they are basic: In a basic solution the concentration of ${\text{OH}}^{-}(\text{aq})$ ions is greater than the concentration of ${\text{H}}^{+}(\text{aq})$ ions.