What percent solution of calcium hypochlorite and detergent in sea water is used?

• A. 9
• B. 3-5
• C. 12
• D. 1-2

Answer: (A)

The main idea here is the standard strength of the calcium hypochlorite solution (with detergent) used in sea water for surface sanitizing. In seawater, the chlorine demand is higher because salts and organic matter consume some of the available chlorine, so a stronger solution is needed to leave an effective residual for disinfection. The nine percent strength is the typical naval standard for this application, providing enough free chlorine to kill microorganisms while remaining practical to handle.

Lower concentrations (three to five percent or one to two percent) wouldn’t overcome the chlorine demand of seawater and wouldn’t reliably disinfect. A much higher concentration (twelve percent) is generally unnecessarily hazardous and beyond standard procedure. Detergent helps wet and spread the solution so it contacts every surface, but the key factor here is the concentration, which is why nine percent is used.