What is the pH value of a neutral substance?

1. 1
2. 7
3. 6
4. 14

The pH value of a neutral substance is 7. The pH scale measures hydrogen ion concentration, with 7 indicating neutrality (equal H⁺ and OH⁻ ions). Pure water at 25°C naturally dissociates into 1×10⁻⁷ M H⁺, defining this equilibrium. Acids (pH <7) donate protons; bases (pH >7) accept them, influencing chemical reactivity and biological functions.