Which of the following substances kills bacteria immediately?

Alcohol is commonly recognized for its ability to kill bacteria effectively and rapidly, which makes it a popular choice for disinfection in various settings. When applied to the skin or a surface, alcohol disrupts the cell membrane of bacteria, leading to cell lysis and resulting in immediate bactericidal action.

For many healthcare applications, concentrations of 60-90% ethanol or isopropyl alcohol are used, which are effective against a broad spectrum of bacteria, including both gram-positive and gram-negative organisms. This rapid action is especially useful in situations where quick antiseptic effects are needed, such as in hand sanitizers or disinfecting surfaces.

While other substances like phenol, hydrogen peroxide, and Betadine also serve as disinfectants, their mechanisms and the time required for bactericidal activity differ. Phenol tends to be less preferred due to its toxicity and irritation potential. Hydrogen peroxide acts as a strong oxidizer and may take longer to achieve its full effect depending on the concentration and conditions. Betadine, containing povidone-iodine, is effective, but its action can be slower and is often used for a broader antiseptic purpose rather than immediate disinfection.

The effectiveness and quick action of alcohol in killing bacteria make it a prime choice in