Classify water using pH: identify the correct statements about neutrality, acidity, and alkalinity with respect to pH values.

Introduction / Context:
pH is a master variable in water quality affecting corrosion, coagulation, disinfectant efficacy, and taste/odor. Correct classification of water based on pH is essential in environmental and municipal engineering.

Given Data / Assumptions:

• pH scale ranges nominally from 0 (strongly acidic) to 14 (strongly alkaline).
• Pure water at 25°C has pH ≈ 7 (neutral).

Concept / Approach:
By definition, pH = −log10[H+]. At 25°C, [H+] = 10^−7 mol/L corresponds to neutral pH 7. Values below 7 indicate higher proton activity (acidic), and values above 7 indicate lower proton activity (alkaline/basic).

Step-by-Step Solution:

Verification / Alternative check:
Any standard water chemistry text or drinking-water standards describe these pH classifications.

Why Other Options Are Wrong:

• Options listing subsets omit one or more correct statements; the complete statement is required.

Common Pitfalls:

• Confusing alkalinity (as titratable carbonate/bicarbonate capacity) with simply having pH > 7; while related, they are distinct concepts.

Final Answer:
All the above