When an acid is diluted, the concentration of hydronium ions (H₃O⁺) per unit volume decreases. This means that the strength of the acid decreases.

The concentration of hydroxide ions (OH⁻) would increase when excess base is dissolved in a solution of sodium hydroxide.

A pH value of less than 7 indicates an acidic solution, while greater than 7 indicates a basic solution. Therefore, the solution with pH = 6 is acidic and has more hydrogen ion concentration than the solution of pH = 8 which is basic.

If the concentration of H⁺ (aq) ions is increased (>10-7) then the solution become acidic and if the concentration of H⁺ (aq) ions is decreased (<10-7) then the solution become basic in nature.

Yes, basic solution also has H⁺ ions. However, their concentration is less as compared to the concentration of OH^– ions that makes the solution basic.

If the soil is acidic and improper for cultivation, then to increase the basicity of soil, the farmer would treat the soil with quick lime or slaked lime or chalk.

Bleaching Powder

Calcium hydroxide [Ca(OH)₂], on treatment with chlorine, yields bleaching powder.