The effectiveness of chemical disinfectants has historically been compared to that of which of the following?

phenol

ethyl alcohol

bleach

formaldehyde

Phenol.

Explanation:

Disinfectant may be defined as the chemical used to kill microorganisms from the inanimate or non-living objects. Disinfectant also provide protection from the pathogens.

Phenol are used as an disinfectant that can denature and coagulate the proteins of pathogens. Phenol is used to clean the floor at homes. Hence, phenol effectiveness has been compared historically with disinfectant.

Thus, the correct answer is option (1).