What instrument is used to test the chemical purity of water by measuring the amount of dissolved solids?

• A. Conductivity Meter
• B. pH Meter
• C. Turbidity Meter
• D. Spectrophotometer

Answer: (A)

Dissolved solids in water become ions that conduct electricity. A conductivity meter measures how well water conducts an electrical current, so higher levels of dissolved ions yield higher conductivity. This makes it a practical proxy for total dissolved solids and thus chemical purity. Temperature can affect readings, so many meters use automatic temperature compensation. The other tools focus on different aspects: a pH meter gauges acidity, a turbidity meter measures cloudiness from suspended particles, and a spectrophotometer analyzes specific substances by light absorption. Therefore, the conductivity meter best assesses chemical purity related to dissolved solids.