Which of the following is a chemical means of controlling microbial growth?

• A. Filtration through a membrane filter
• B. Using bleach (sodium hypochlorite) to disinfect surfaces
• C. Exposure to ultraviolet (UV) radiation
• D. Autoclaving surgical instruments

Answer: (B)

Verified step by step guidance

1. Understand the difference between physical and chemical methods of controlling microbial growth. Physical methods involve physical processes or treatments, while chemical methods use substances that kill or inhibit microbes.
2. Review each option and classify it as either a physical or chemical method: Filtration through a membrane filter is a physical method because it physically removes microbes from a liquid or air.
3. Exposure to ultraviolet (UV) radiation is a physical method because it uses light energy to damage microbial DNA, preventing replication.
4. Autoclaving surgical instruments is a physical method involving heat and pressure to sterilize equipment.
5. Using bleach (sodium hypochlorite) to disinfect surfaces is a chemical method because bleach is a chemical agent that kills microbes by oxidizing cellular components.