As the concentration of hydronium ions increases, the pH value _______.

Correct option is B

Correct Answer: (B) decreases

Explanation:
The pH scale is a measure of the concentration of hydronium ions (H₃O⁺) in a solution. It is given by the formula:

pH=−log⁡[H₃O⁺]

• When the concentration of hydronium ions increases, the logarithmic function in the formula results in a lower pH value.
• A low pH indicates a higher acidity, while a high pH corresponds to a lower acidity or higher alkalinity.
• In an acidic solution, the [H₃O⁺] is high, leading to a low pH value (typically below 7).
• Conversely, in a basic solution, the [H₃O⁺] is low, leading to a higher pH value (above 7).

Thus, as the concentration of hydronium ions increases, the pH value decreases.

Information Booster:

• pH Scale: Ranges from 0 to 14, where pH 7 is neutral, pH < 7 is acidic, and pH > 7 is basic.
  
• Strong Acids (HCl, H₂SO₄, HNO₃) have high H₃O⁺ concentration and low pH values (close to 0–2).
  
• Weak Acids (CH₃COOH, H₂CO₃) have moderate H₃O⁺ concentration and pH values around 4–6.
  
• pH of Pure Water is 7 at 25°C, meaning it is neutral.
  
•  The pH scale is logarithmic, meaning that a pH change of 1 unit represents a 10-fold change in [H₃O⁺] concentration.