Which term describes the measure of the acidity or alkalinity of a solution?

• A. Lattice
• B. Pores
• C. Shrinkage cavity
• D. pH

Answer: (D)

The measure of acidity or alkalinity of a solution is described by pH. pH is a numeric scale that expresses the hydrogen ion activity in a solution: lower values mean more acidic, higher values mean more alkaline, and a pH around 7 is neutral at standard conditions. This single term is specifically used to quantify how acidic or basic a solution is, which is why it’s the correct choice. The other terms describe physical features or defects—lattice refers to the orderly arrangement of atoms in a crystal, pores are openings in a material, and shrinkage cavity is a defect that can form during casting. None of those describe how acidic or basic a solution is.