MCQ Detailed View

The pH scale is a numerical scale ranging from 0 to 14 that measures how acidic or basic a solution is. It is based on the concentration of hydrogen ions (H⁺) in a solution. Lower values indicate acidity, higher values indicate alkalinity, and the middle value represents neutrality. A solution with a pH of 7 is neutral, such as pure water.

Alkaline solutions, also known as basic solutions, begin from a pH value just above 7 and extend to 14. More specifically, the alkaline range is considered from pH 8 to 14. In this range, the concentration of hydroxide ions (OH⁻) is greater than the concentration of hydrogen ions (H⁺). This imbalance gives the solution its basic character.

Examples of substances with alkaline pH include household ammonia (around pH 11), baking soda solution (around pH 9), and sodium hydroxide solution (pH 13 to 14). These solutions are slippery to touch, taste bitter, and can neutralize acids through chemical reactions.

On the acidic side of the pH scale, values less than 7 indicate solutions where hydrogen ions are more concentrated than hydroxide ions. Examples include lemon juice (pH 2) and vinegar (pH 3).

The pH scale is logarithmic, meaning that each unit change represents a tenfold change in hydrogen ion concentration. For example, a solution with pH 8 is ten times less acidic than a solution with pH 7.

In analytical chemistry, pH measurement is critical for titrations, chemical reactions, and quality control in laboratories. Maintaining correct pH is also essential in biological systems, agriculture, environmental monitoring, and industrial processes.

Thus, the alkaline side of the pH scale clearly starts at 8 and continues up to 14, representing solutions that are basic in nature.